royal canadian air force neck- and back-trouble research · musculoskeletal trouble within...

Royal Canadian Air Force Neck- and Back-Trouble Research A Historical Review

Adam Xiao Philip S. E. Farrell DRDC – Toronto Research Centre

Defence Research and Development Canada Reference Document DRDC-RDDC-2016-D031 July 2016

IMPORTANT INFORMATIVE STATEMENTS This work is a deliverable under 03aa Air Human Effectiveness Project and the Neck and Back Trouble Mitigation Solutions Work Breakdown Element.

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© Her Majesty the Queen in Right of Canada, as represented by the Minister of National Defence, 2016

© Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la Défense nationale, 2016

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Abstract

Griffon Helicopter aircrew neck trouble is likely to distract aircrew from performing flying tasks and, in the extreme, may cause them to be grounded. Rotary-wing aircrew back pain issues have been researched in the RCAF since the 1980’s, while neck pain came to the forefront in the 2000’s.

In cases of both neck and back trouble research, a number of Canadian research efforts were conducted ranging from understanding the problem to developing solutions. An effort to reinvigorate aircrew neck trouble research began after a 2012 Neck Strain Workshop, with a clear mandate to deliver solutions. This paper consolidates the research and studies that were performed for Royal Canadian Air Force (RCAF) on back and neck trouble leading up to current efforts. From this review, various research gaps and lessons learned are identified.

Research gaps include: a) investigating the underlying mechanisms to musculoskeletal neck pain, b) finding solutions for musculoskeletal trouble other than neck, and c) developing solutions to musculoskeletal trouble within rotary-wing, fast-jet, army and navy communities. Key lessons learned include: a) multi-faceted problems (such as neck-trouble amongst aircrew) require multi-disciplinary teams to understand the problem and develop solutions, and b) oversight helps align research to a central goal, which may be aided with use of a common conceptual framework.

Significance to Defence and Security

This work is part of the Royal Canadian Air Force (RCAF) and Defence Research and Development Canada’s (DRDC’s) Air Agile Program Air Human Effectiveness project (03aa) Neck and Back Trouble Mitigation Solutions Work Breakdown Element (WBE). It also has strong ties with the North Atlantic Treaty Organisation (NATO) Science and Technology (STO) Human Factors and Medicine (HFM) Panel HFM-252 Research Task Group (RTG) on Aircrew Neck Pain.

One of the intermediate outcomes as outlined in the Air Agile Program Brief is to “Improve health and safety of operational RCAF personnel by exploring causes and solutions for aero-medical challenges such as hypoxia and neck strain injuries.” This paper sets the historical context for the current 03aa project.

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Résumé

La douleur de cou qui est vécu par des membres d’équipage d’hélicoptère Griffon peut être distraire ces membres de l’exécution des tâches de vol et, à l’extrême, peut les causer à être mis à la terre. Les problèmes de la douleur de dos entre des membres d’équipage d’hélicoptère ont été étudiés dans l’Aviation royale canadienne (ARC) depuis les années 1980, alors que la douleur de cou est venue à l’avant-garde dans les années 2000.

Dans les cas des recherches sur des problèmes de cou et de dos, un certain nombre d’efforts de recherche canadiens ont été menées pour comprendre le problème et développer des solutions. Un effort pour relancer ces recherches la douleur au cou pour les équipages a commencé après une Atelier de 2012 sur ce sujet, avec un mandat clair pour offrir des solutions. Alors, ce document regroupe les recherches et les études qui ont été effectuées pour l’ARC sur le dos et le cou des problèmes jusqu’à efforts actuels. De cet examen, diverses lacunes de la recherche et les leçons apprises sont identifiés.

Les lacunes de la recherche comprennent: a) étudier les mécanismes fondamentaux de la douleur de cou musculo-squelettique, b) trouver des solutions pour des problèmes musculo-squelettique pour des autre parts de cours comme le dos, et c) développer des solutions à des problèmes musculo-squelettiques pour des autres hélicoptères, des rapide-jets, l’armée et la marine. Les leçons apprises comprennent: a) des problèmes à facettes multiples (comme la douleur de cou entre des membres d’équipage) ont besoin des équipes multidisciplinaires pour comprendre le problème et développer des solutions, et b) la surveillance permet d’aligner la recherche d’un objectif central, qui peut être aidé avec l’utilisation d’un cadre conceptuel commun.

Importance pour la défense et la sécurité

Ce travail fait partie du project de l’Aviation royale canadienne (ARC) et recherche et développement pour la défense Canada (RDDC) qui s’appelle « Air Agile Programme Air Human Effectiveness Project (03aa) Neck and Back Trouble Mitigating Solutions ». Il a également des liens étroits avec l’Organisation du Traité de l’Atlantique Nord Organisation (OTAN) organisation de scientifique et recherche (STO) Facteurs humains et médecine (HFM) groupe HFM-252 (RTG) s’appelle « Aircrew Neck Pain ».

L’un des résultats intermédiaires tels que décrits dans le dossier de project 03aa consiste à «améliorer la santé et la sécurité du personnel de l’ARC opérationnelles en explorant les causes et les solutions pour les défis aéromédicaux tels que l’hypoxie et du cou microtraumatismes. » Ce document présente le contexte historique pour le projet de 03aa.

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Table of Contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Significance to Defence and Security . . . . . . . . . . . . . . . . . . . . . . i Résumé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii Importance pour la défense et la sécurité . . . . . . . . . . . . . . . . . . . . ii Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Neck Research Chronology . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Pre-1980’s – Emergence of the Rotary-Wing Aircraft . . . . . . . . . . . 2

2.2 1980’s – Helicopter Backache Problem . . . . . . . . . . . . . . . . 2

2.2.1 (1985) AGARD meeting on Backache and Back Discomfort . . . . . . 2

2.2.1.1 Biomechanical Approach . . . . . . . . . . . . . . . 3

2.2.1.2 Vibration Exposure . . . . . . . . . . . . . . . . . . 3

2.2.1.3 Seat Isolation System . . . . . . . . . . . . . . . . . 3

2.2.2 (1985) Backache in the CH-113 Labrador Helicopter . . . . . . . . . 4

2.2.3 (1988) Individually Moulded Fibreglass Lumbar Supports . . . . . . . 4

2.3 1990’s – Helmet Mounted Devices and Mass Properties . . . . . . . . . . 5

2.3.1 (1991) Canadian Forces SPH-5 Helmet Acquisition . . . . . . . . . 6

2.4 2000’s – Helicopter Neck Strain Problem and Solutions . . . . . . . . . . 6

2.4.1 (2004) Survey on NVG-induced Neck Strain . . . . . . . . . . . . 6

2.4.1.1 Survey Design . . . . . . . . . . . . . . . . . . . 6

2.4.1.2 Neck Pain Mechanism . . . . . . . . . . . . . . . . 7

2.4.1.3 Aircrew Behavioural Differences . . . . . . . . . . . . 7

2.4.2 (2004) Whole-Body Vibration Mitigation . . . . . . . . . . . . . 7

2.4.2.1 Individual Blade Control (IBC) . . . . . . . . . . . . . 7

2.4.2.2 Adaptive Seat Mounts . . . . . . . . . . . . . . . . 8

2.4.2.3 Passive Seat Cushions . . . . . . . . . . . . . . . . 8

2.4.3 (2007) Muscle Metabolism, Biomechanics, and Exercise . . . . . . . 9

2.4.3.1 Trapezius Muscle Metabolism . . . . . . . . . . . . . 9

2.4.3.2 Cumulative Loading . . . . . . . . . . . . . . . . . 9

2.4.3.3 Predictive Logistic Regression Equation . . . . . . . . . . 9

2.4.3.4 Exercise Therapy . . . . . . . . . . . . . . . . . . 10

2.4.4 (2007) Neck Support Systems . . . . . . . . . . . . . . . . . 10

2.4.5 (2008) Finite Element Modelling . . . . . . . . . . . . . . . . 12

2.4.5.1 Royal Military College . . . . . . . . . . . . . . . . 13

2.4.5.2 Homat-Tech . . . . . . . . . . . . . . . . . . . . 13

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2.4.6 (2009) Helmet-Systems Effects on Neck Muscle Demands . . . . . . 14

2.5 Post-2012 – Near-Term Solutions . . . . . . . . . . . . . . . . . . 14

2.5.1 Neck Strain Workshop . . . . . . . . . . . . . . . . . . . . 14

2.5.2 Identification and Proposal of Near-Term Solutions . . . . . . . . . 15

2.5.3 (03pg/13pg) Neck Strain Applied Research Project . . . . . . . . . 15

2.5.4 Neck- and Back-trouble Mitigating Solutions . . . . . . . . . . . 16

3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

List of Symbols/Abbreviations/Acronyms/Initialisms . . . . . . . . . . . . . . . 27

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List of Figures

Figure 1: Proposed seat isolation system by CAE Electronics adapted from G-seat (van Vliet et al., 1985). . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2: Example of helmet-system: helicopter integrated helmet “KNIGHT HELM” from GEC Avionics (Bohm & Schreyer, 1991). . . . . . . . . . . . . . 5

Figure 3: Example of an adaptive seat mounts active vibration mitigation system. This prototype uses two stacked piezoelectric actuators (Chen et al., 2011). . . . . 8

Figure 4: Prototype neck support system: helmet attachment concept (HAC) (Bailey, 2013). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 5: Prototype neck support system: hooded collar vest (HCV) (Bailey, 2013). . . 11

Figure 6: Braced collar concept (BCC) for neck support system (Bailey, 2013). . . . . 12

Figure 7: Example of a spine finite element model (Moglo et al., 2012). . . . . . . . 13

Figure 8: List of Proposed solutions from Toronto Rehabilitation Institute (TRI) and Queen’s University (QU) (Chafe, 2014). . . . . . . . . . . . . . . . . 16

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1 Introduction

A description of the aircrew neck pain problem can be found in other published literature reviews (Harrison, Coffey, Albert, & Fischer, 2015; McLaughlin, 2013). This Reference Document archives research related to aircrew neck and back trouble conducted for the Royal Canadian Air Force (RCAF) from pre-1980 to present, and identifies research gaps and lessons learned. These gaps and lessons learned can be used to develop future related studies.

1.1 Background

RCAF aircrew experience various levels of neck- and back-trouble. ‘Trouble’, as a general term, includes pain, discomfort, injury, strain, or ache. These terms are used inter-changeably amongst researchers and are used synonymously in this report.

Since the first full-scale production helicopter was built in 1942, anecdotal reports by test pilots noted the peculiar characteristics of rotary-wing flight:

“Shaken on an uncomfortable platform for an hour of flight, the pilot is in a hurry to land and return to the hangar, to tend to his aches (Delahaye et al., 1970).”

Despite research efforts by Defence Research and Development Canada (DRDC), Directorate of Technical Airworthiness and Engineering Support (DTAES), and the Surgeon General,1 the problem of ‘aches’ amongst helicopter pilots in the RCAF still persists. In a 2004 RCAF survey, 82% of CH-146 Griffon helicopter aircrew reported neck pain (Adam, 2004). This finding was further supported in a recent 2014 RCAF survey where 75% of Griffon helicopter aircrew reported neck pain (Chafe & Farrell, 2016).

Chapter 2 summarises neck and back pain research performed by DRDC, DTAES, and Surgeon General in support of RCAF aircrew, and presents them in chronological order starting with pre-1980 and systematically progressing up to the beginning of the current project. Chapter 3 identifies key lessons learned through this review. In addition to this, a gap analysis suggests research areas both to be pursued and to be avoided. The conclusion chapter summarises this report and makes recommendations for future studies.

1 Canadian Forces Environmental Medicine Establishment (CFEME) is not only a client (as part of Surgeon General and CFHS) for neck strain research but has also participated in producing deliverables for the various projects.

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2 Neck Research Chronology

This chapter provides a listing of Canadian neck pain research efforts including their objectives and deliverables. The scope of this review was limited to research efforts that were funded directly by the Canadian Department of National Defence (DND) through DRDC, DTAES, and the Surgeon General with support from the National Research Council of Canada (NRCC) through a DND/NRCC memorandum of understanding. This chapter is organised chronologically by decades starting with pre-1980’s research.

A literature search was conducted using the following, or combinations of, keywords: ‘neck’, ‘helicopter’, ‘back’, ‘ache’, ‘trouble’, ‘aircrew’, ‘spine’, ‘pain’, ‘strain’, ‘night vision goggles’ and ‘vibration’. The following online databases were consulted: Canadian Defence Information Database (CANDID) and Defense Technical Information Center (DTIC). The DRDC Toronto Research Centre library was also a source of hardcopy DCIEM quarterly and annual reports, as well as dated meeting proceedings. Meeting minutes from Aeromedical Policy and Standards Committee (APSC) were also consulted to track research decisions and progress. All matched articles and their bibliographies were reviewed for relevant information.

2.1 Pre-1980’s – Emergence of the Rotary-Wing Aircraft

Recall that the first full-scale production helicopter was built in 1942. Beginning in the 1950’s, militaries began implementing helicopters in operations. Later, extensive guidelines were discussed for rotary-wing flight concerning aeromedical, environmental and other factors. Helicopter aircrew backache emerged as one such topic of discussion (Schulte-Wintrop & Knoche, 1978). An early seminal series of French studies provided clinical insight on the phenomenon of spinal injury prevalent in aerospace medicine (Delahaye et al., 1982; Delahaye et al., 1970), which defined the problem through radiology, then investigated potential causal factors of vibration and seated posture ergonomics.

2.2 1980’s – Helicopter Backache Problem

2.2.1 (1985) AGARD meeting on Backache and Back Discomfort

As a result of survey findings from various nations that reported backache in helicopter pilots (Delahaye et al., 1982; Fitzgerald & Crotty, 1972; Schulte-Wintrop & Knoche, 1978; Shanahan, 1984), an Advisory Group for Aerospace Research and Development (AGARD), formerly an agency of NATO, specialist’s meeting No. 378 led by Dr. Jack Landolt of the Defence and Civil Institute of Environmental Medicine (DCIEM), was held on “Backache and Back Discomfort”. This international effort addressed the occupational backache problem present across military platforms (most notably in aviators), with representatives from eight NATO nations and two non-NATO countries in attendance. A broad scope of research was examined which included defining the aircrew backache problem, developing etiological factors, and proposing solutions.

Members of DCIEM (the former name of the DRDC Toronto Research Centre) attended this AGARD conference, with several research groups each presenting relevant projects (Beevis


& Forshaw, 1985; Bowden, 1985; van Vliet, McKinnon, & Kruk, 1985). DCIEM scientists also sat on the specialist meeting Technical Programme Committee, which was responsible for synthesising the technical evaluation report (Landolt, 1985). Thus, DCIEM was fully engaged in research in the area of helicopter aircrew backache problems in the 1980s.

2.2.1.1 Biomechanical Approach

A literature review was compiled (Bowden, 1985), which speculated upon the mechanism and causal factors of backache. It was proposed that postural fatigue in specific muscles—rather than spinal injury—was the cause of pain. Cockpit2 vibration compounded the mechanical stresses on these back muscles. Engineering solutions such as cockpit ergonomics and vibration mitigation were suggested as promising avenues of research. International collaboration was recommended to gain understanding of the underlying mechanisms of backache before solutions were to be designed. Specifically, postural muscular fatigue, as a possible causal factor, was recommended for closer examination. Quantitative techniques such as electromyography (EMG) were suggested to explore muscle fatigue.

2.2.1.2 Vibration Exposure

At the time, International Standards Organisation (ISO) provided vague guidelines with respect to human exposure to vibration (ISO, 1982). A DCIEM study on vibration in armoured ground vehicles was presented (Beevis & Forshaw, 1985); a high prevalence of back pain was noted, but it was not possible to attribute causality due to insufficient sample size. DCIEM researchers conducted studies measuring vibration and noise levels on various vehicle platforms, which included helicopters (Forshaw, Crabtree, & Cruchley, 1978).

2.2.1.3 Seat Isolation System

An active vibration mitigation seat isolation (Figure 1) proof-of-concept system was proposed by DCIEM contractor CAE Electronics Ltd. (van Vliet et al., 1985). This system was adapted from high-G simulator seats that featured a hydraulically articulated seat cushion matrix, which delivered localised forces to the seat bottom and back. Lab tests showed the seat was effective in suppressing vibrations in the target 3 to 8 Hz range. It was recommended that such innovations be delivered in conjunction with ergonomic interventions such as side-arm controls. However, this system was not fully developed and other recommended ergonomic interventions were never pursued.

2 Around this time the focus of the research was on pilots in the cockpit, and less so on non-pilot aircrew members in the cabin.


Figure 1: Proposed seat isolation system by CAE Electronics

adapted from G-seat (van Vliet et al., 1985).

2.2.2 (1985) Backache in the CH-113 Labrador Helicopter

An Unsatisfactory Condition Report (UCR) filed by 442 Transport and Rescue squadron led to DCIEM being tasked by National Defence Headquarters (NDHQ) to investigate the problem (Beach, 1985). This UCR complained of the uncomfortable pilot’s seat in the CH-113 Labrador helicopter inducing back pain and discomfort over long search and rescue (SAR) missions. A questionnaire was designed to characterise the occurrence and symptomology of back pain. Symptoms commonly reported were of a dull pain in the lower back, which occasionally distracted attention and were largely chronic in nature. The questionnaire also revealed a significantly larger proportion of pilots who exercised daily in the ‘no backache’ versus ‘backache’ response groups. The static asymmetric forward leaning attitude was cited as a possible causal factor. An ergonomic assessment of the seat showed compliance with military standards on the basis of seat angles and proportions. However, it is common for pilots to lean forward off of the seat back while flying.

It was recommended to use seat cushions with lumbar support. An improved seat cushion was thought to provide improved pilot-seat contact and thus induce an ideal lordosis of the lumbar spine. Also, it was recommended that a regular exercise program be made available to pilots.

2.2.3 (1988) Individually Moulded Fibreglass Lumbar Supports

Results of a flight trial were presented for individually molded fibreglass lumbar supports in both fixed wing and rotary-wing pilots (Popplow & Bossi, 1988). Through questionnaire responses, partial to complete alleviation of post-flight back pain was found in the majority of fixed wing


pilots as well as in many rotary-wing pilots. The authors recommended that these lumbar supports be part of aviation life support equipment, with flight surgeons as referral agents.

2.3 1990’s – Helmet Mounted Devices and Mass Properties

Technological innovation in the 1990’s culminated in helmet mounted displays (HMD), night vision goggles (NVG), visors and ballistic masks. HMDs (example shown in Figure 2) include situational awareness and weapons cueing systems such as heads up displays (HUD) and helmet mounted cueing systems (HMCS). HMDs, NVGs, visors and masks will collectively be subsequently referred to as ‘helmet-systems’ for simplicity. Although these technologies were designed to improve capability and offered operational advantages, they came under heavy scrutiny with regard to human factors, operational performance, and more. Specifically, the mounting of avionics onto the helmet creates an external load on the human operator which creates an internal load on the tissue.

While these discussions regarding helmet-systems addressed several human factors topics, the issue of helmet-system induced chronic pain did not arise since these devices had not been in service for any great length of time. As it became clear that helmet-systems imposed adverse mechanical stresses on human operators, namely the cervical spine, 1990’s research in the United States began to examine helmet-system mass properties (total mass, centre of mass (CoM) and moment of inertia (MoI)) and their impact on the spines of wearers (Alem, Meyer, & Albano, 1995; Butler, 1992, 1997; McEntire & Shanahan, 1998). A literature review (Manoogian, Kenedy, & Duma, 2005), conducted by the U.S. Army Aeromedical Research Laboratory, provides an exhaustive summary of 1990’s helmet-systems mass properties research.

Figure 2: Example of helmet-system: helicopter integrated helmet “KNIGHT HELM”

from GEC Avionics (Bohm & Schreyer, 1991).


2.3.1 (1991) Canadian Forces SPH-5 Helmet Acquisition

A Canadian acquisition program was initiated in 1988 to replace the dated DH411 helicopter aircrew helmet (Melejczuk, Thorne, Rylands, & Scharnitzky, 1991). The motivation for this new acquisition was to provide updated technology and better overall performance. Two helmet options—the Advanced Lightweight Protective Helmets for Aircrew (ALPHA) and the Gentex Sound Protective Helmet Number 5 (SPH-5)—were subject to vigorous testing under the following parameters: mass properties, ruggedness, visual field, comfort & fitting, impact attenuation, sound attenuation, communications, visors and NVG compatibility.

Experimentally proven helmet mass properties recommendations (for neck pain reduction) did not exist at this time. Therefore, intuitive guidelines were followed. For example, mandatory requirements included that the helmet “be as light as possible” and that the CoM be “located as close as possible to the [CoM] of the human head”. It should be noted that no requirements in terms of Moments of Inertia (MoI) were recommended. Furthermore, these guidelines had in mind the helmet only, and not (explicitly) the helmet with NVG peripherals.

Although both SPH-5 and ALPHA showed significant improvements over the previous DH411, the SPH-5 showed a greater potential for modification of fit and mounting of future NVGs. The SPH-5 was ultimately chosen as the replacement helmet and implemented across all CAF helicopter aircrew. The SPH-5 is currently used by approximately 25% of Griffon aircrew (Chafe & Farrell, 2016).

2.4 2000’s – Helicopter Neck Strain Problem and Solutions

At the turn of the millennium, the problem of helicopter aircrew neck pain began to emerge and it was being documented by a number of nations based on aircrew surveys. These national surveys all pointed to the large prevalence of neck pain present in their rotary-wing aircrew populations (Adam, 2004; Ang & Harms-Ringdahl, 2006; Fraser, Crowley, Shender, & Lee, 2015; van den Oord, Loose, Meeuwsen, Sluiter, & Frings-Dresen, 2010). Thus, research efforts in individual countries sought to understand the problem and its causality, which lead to evaluation of mitigating solutions.

2.4.1 (2004) Survey on NVG-induced Neck Strain

An ergonomic assessment of flight engineers (FE) at 403 squadron flying the CH-146 Griffon recommended investigation to establish any correlation between FE spine injuries and mechanical loading due to equipment such as NVGs (Wierstra, 2001). In response to this, a 2004 exploratory study investigated NVG-induced neck strain in the CH-146 Griffon helicopter aircrew (both pilots and FEs) (Adam, 2004). A detailed questionnaire collected subjective pain characteristics associated with flight experience and NVG use.

2.4.1.1 Survey Design

The 2004 Canadian survey included both Griffon (employ NVGs) and CH-124 Sea King (do not employ NVGs) aircrew (Adam, 2004). This design provided an opportunity to compare neck


trouble for those who wore NVGs to those who did not wear NVGs in operations. The results showed that perceived flight-related neck pain was significantly higher for Griffon aircrew than Sea King aircrew in both pilots and flight engineer populations. Thus, while there are many other factors that may differ between tactical helicopter and maritime helicopter flying operations, NVG usage was expected to be a contributing factor to flight-related neck pain.

2.4.1.2 Neck Pain Mechanism

The 2004 Canadian survey (Adam, 2004) asked about neck pain intensity, duration and persistence. Interestingly, the author noted no significant difference in these pain characteristics between Griffon and Sea King aircrew. It was thus hypothesized that there existed common causal factors between the two communities. Thus, a key recommendation coming from this study was to further examine the pathophysiology of neck pain.

2.4.1.3 Aircrew Behavioural Differences

The 2004 Canadian survey (Adam, 2004) included an open comments section. Trends were observed in the comments alluding to behavioural differences between pilot and FE aircrew. Indeed, pilots and FE’s are exposed to different workspace demands including different tasks, seats, displays and controls while performing their jobs. Several pilot respondents indicated that the Control Display Unit (CDU) location forced them to adopt a prolonged awkward position in order to view the display. FEs noted that out-the-door operations were physically demanding and led to fatigue. The study did not find significant differences in flight-related neck pain incidence between Griffon pilots and FEs. It was recommended that behavioural and workspace differences in neck pain development be more closely examined in future.

2.4.2 (2004) Whole-Body Vibration Mitigation

A common feature of rotary wing operation is structural vibration during flight due to the complex interaction of rotor blades moving through turbulent air (Kretz & Larche, 1980). Recall that the association between whole-body vibration and spinal pain has been observed since the conception of rotary wing flight (Delahaye et al., 1970). As such, mitigation of vibrations felt by the operators may reduce the prevalence of neck pain. Various engineering approaches in vibration mitigation have been explored at National Research Council of Canada (NRCC) initially funded by DTAES-6 and currently funded through a DND/NRCC memorandum of understanding (Chen & Wickramasinghe, 2005; Chen, Wickramasinghe, & Zimcik, 2009; Chen, Wickramasinghe, & Zimcik, 2010; Chen, Wickramasinghe, & Zimcik, 2011; Chen, Zimcik, Wickramasinghe, & Nitzsche, 2004; Wickramasinghe, Yong, & Zimcik, 2008; Wickramasinghe, Ozer, & Zimcik, 2005).

2.4.2.1 Individual Blade Control (IBC)

Individual Blade Control (IBC) is an active control technique in which rotor blades roots are actively actuated at the rotor hub in order to mitigate vibration propagation through the helicopter (Chen et al., 2004). A ‘Smart Spring’ concept was developed which acts as an Actively Tunable Vibration Absorber (ATVA) (Chen & Wickramasinghe, 2005; Chen et al., 2004;


Wickramasinghe et al., 2008). This system, placed between the blade root and the rotor hub, varies the stiffness and therefore the dampening properties of the rotor blade. A proof of concept hardware was prototyped and tested in mechanical shaker and wind tunnel conditions (Chen et al., 2004), showing a 62% suppression in blade root displacement.

2.4.2.2 Adaptive Seat Mounts

Vibrations were measured in-flight, which revealed peaks corresponding to resonant frequencies of the rotor blade system (Wickramasinghe et al., 2005). It was found that high frequencies were adequately supressed through the current in service seat cushion. However, low frequency vibrations (~5.12 Hz) were being amplified at the helmet level. Thus, adaptive seat mounts were investigated to mitigate vibrations felt by the pilot (Chen et al., 2009; Chen et al., 2011). Based on simulation results, the actuation authority (displacement and force) of the motor driving the seat mount was determined. An electrodynamic actuator was selected for the first proof-of-concept prototype (Chen et al., 2009). A later active seat mount configuration was trialed employing piezoelectric smart materials actuators (Figure 3) (Chen et al., 2011). Closed-loop control experiments of the prototype adaptive seat mounts noted a 33% decrease in vibration measured at the mannequin abdomen (Chen et al., 2010).

Figure 3: Example of an adaptive seat mounts active vibration mitigation system.

This prototype uses two stacked piezoelectric actuators (Chen et al., 2011).

2.4.2.3 Passive Seat Cushions

Recall that the current in-service helicopter seat cushion is effective at suppressing high (> 5–7 Hz) but not low (<5 Hz) frequency vibrations (Wickramasinghe et al., 2005). Thus seat cushion properties were studied as a passive vibration mitigation system (Chen et al., 2010). These experiments involved in-flight trials for a number of seat cushion materials and configurations: uniprene, monoprene, Iso and sorbothane pads of 1", 0.25" and 0.5" thicknesses in addition to the current in-service seat cushion. Of these configurations, it was found that the combination of a


urethane pad of 1" with the Bell-412 original cushion provided most significant suppression of vibration, specifically 1/rev (~5 Hz) and 4/rev (~20 Hz) harmonics. These preliminary results show the efficacy of passive approaches in delivering significant vibration reduction. It was recommended that a combination of both passive and active vibration mitigation approaches be utilised in a synergistic vibration mitigation system.

2.4.3 (2007) Muscle Metabolism, Biomechanics, and Exercise

A series of studies was launched through collaboration of University of Regina and University of New Brunswick, funded by the Canadian Forces Quality of Life grant and the Military Health Research Program (DND/CFHS). These studies (Forde et al., 2011; Harrison, Neary, Albert, & Croll, 2011, 2012; Harrison et al., 2009; Harrison et al., 2010; Harrison et al., 2007a, 2007b, 2007c; Salmon et al., 2013) focused on muscle function as it relates to neck pain. Near-infrared Spectroscopy (NIRS) techniques were used in the understanding of muscle metabolism due to mechanical loading. These were then combined with pre-existing biomechanical metrics, such as EMG and MVC (Maximum Voluntary Contraction) force, to paint a more complete picture of the neck strain problem. Finally, muscular conditioning programs were trialed and proposed as a solution for the neck pain problem.

2.4.3.1 Trapezius Muscle Metabolism

Metabolic and hemodynamic demands of the trapezius muscles, measured through NIRS, were tested under various experimental conditions. For example, it was found that NVG usage during simulated night flights versus day flights (without NVGs) was associated with increased metabolic stress of trapezius muscles (Harrison et al., 2007c). It was observed that the use of counterweights decreased metabolic stress on trapezii (Harrison et al., 2007b). Cockpit ‘seat side’ was examined, however no difference was observed in metabolic stress of the trapezii between the pilot and co-pilot positions (Harrison et al., 2007a). A difference between left and right trapezii was found throughout all experiments. The asymmetric seated flying posture was suggested as a potential cause factor for this difference.

2.4.3.2 Cumulative Loading

Cervical spine cumulative loading in a motion-based Griffon helicopter simulator was studied (Forde et al., 2011). Cumulative loading is defined as the total external force experienced by the operator throughout a mission. Video footage from simulated day (no NVG) and NVG-equipped night missions were analysed to determine force characteristics on a static frame-by-frame basis. It was found that night flights showed significantly larger cumulative as well as peak loads for compression, shear and lateral moments. Additionally, it was noticed that a significantly higher proportion of NVG night flights were spent in non-neutral neck positions (i.e., with higher biomechanical strain) relative to day flights.

2.4.3.3 Predictive Logistic Regression Equation

A combinatorial approach was adopted in order to bring together previously studied factors (Harrison et al., 2011; Harrison et al., 2009). EMG measurements were made for 100% and 70% MVC


endurance conditions for isometric flexion, extension, and lateral flexion of the cervical spine. NIRS data was collected concurrently. In addition, a short questionnaire was administered to probe neck pain prevalence as well as basic anthropometric and demographic characteristics. From these factors as well as physical fitness test results, a predictive logistic regression equation was produced (Harrison et al., 2012):3

Neck pain = 𝑒−(27.12−18.36 𝐻𝑡+1.37 𝑁𝑉𝐺𝑚𝑎𝑥) [1 + 𝑒−(27.12−18.36 𝐻𝑡+1.37 𝑁𝑉𝐺𝑚𝑎𝑥)]⁄

Here, the factors height (Ht) and longest single NVG mission (NVGmax) were found to have a high predictive value for neck pain (r2 = 0.78). This series of studies was the first to combine EMG, NIRS data with chronicled demographic reports.

2.4.3.4 Exercise Therapy

The effects of exercise modalities on previously described EMG biomechanical properties were examined (Salmon et al., 2013). These modalities included neck coordination training program (CTP) and an endurance training program (ETP). It was found, most notably in CTP group, but also in ETP group, that exercise significantly increased MVC force and 70% MVC endurance. Recommendations were made for further investigation of individualized exercise studies to be implemented in aircrew procedures.

2.4.4 (2007) Neck Support Systems

Engineering Services Incorporated (ESI) was contracted by DRDC Toronto to develop a novel neck support system (NECSUS) (Bailey, 2012; Fan, Lu, Stehlik, Chen, & Goldenberg, 2008; Jahanshah et al., 2006; Jahanshah et al., 2005). The objective was to provide mechanical support for the neck under helmet-system loads.

Through various design iterations and testing phases, several prototypes resulted from the project. The helmet attachment concept (HAC) featured a vest worn by the user with a spring which anchored to the back of the helmet (Figure 3). This articulated spring offers resistance to flexion as well as rotational neck movements. Additionally, extension support was provided through buckling of the integrated supporting elements. The hooded collar vest (HCV) featured shape memory alloy actuators with tunable stiffness (Figure 4). Positioned around the neck in a collar-like fashion, support could be delivered at various locations during different neck movements as needed. The braced collar concept (BCC) counteracted both compressive as well as flexor muscle loads during neck flexion (Figure 5). The BCC presented as a chin brace collar which was driven by a motor. This model preserved the range of motion of the neck with the exception of flexion.

3 1.37 was originally L37 but was changed with permission from the author.


Figure 4: Prototype neck support system: helmet attachment concept (HAC) (Bailey, 2013).

Figure 5: Prototype neck support system: hooded collar vest (HCV) (Bailey, 2013).


Figure 6: Braced collar concept (BCC) for neck support system (Bailey, 2013).

2.4.5 (2008) Finite Element Modelling

The application of finite element modelling techniques was initiated by several Canadian researchers around 2008 in order to gain a deeper understanding of complex cervical spine physiology. Figure 7 shows an example of a finite element model of the cervical spine and head. Such a modelling approach was proposed as a time and cost effective means to understand the neck structures and tissue properties which is otherwise clinically invasive and not feasible to study. Two concurrent projects were undertaken at Royal Military College of Canada (RMC) (Moglo, 2014; Moglo, Mesfar, & Mustafy, 2012) funded by DTAES-6 and Homat-Tech (Behdinan & Bahramsharhi, 2012a, 2012b) contracted by DRDC – Toronto. Both independent efforts had a common objective of creating a high-fidelity neck model from which one could begin to understand neck trouble mechanisms and develop experimental protocols to test the models.


Figure 7: Example of a spine finite element model (Moglo et al., 2012).

2.4.5.1 Royal Military College

The purpose of this FE modelling effort was to better understand the complex pathophysiology and pathogenesis of cervical pain (Moglo et al., 2012). A segmental spine model was generated which included C1–C7 & T1 vertebrae, skull, all ligaments, intervertebral disks (IVD), and zygapophyseal (facet) cartilage joints. It was believed that, with such a model, one would be able to explore the hypothesis that the origin of pain need not be spatially associated with where the pain is felt.

2.4.5.2 Homat-Tech

The motivation behind the development of this model was to create a highly detailed and validated model to better understand mechanical injury mechanisms (Behdinan & Bahramsharhi, 2012a, 2012b). A segmental model of the neck was developed, which included C0–C7 & T1 vertebrae, five ligaments, IVD, and facet joints. An emphasis was placed on the mathematical representation of the material properties of tissues. These principles were applied to the modelling of IVD and facet


joints, which were thought to withstand the majority of helmet-system loading. This model was found to be sensitive to detect helicopter helmet loadings between 10 and 36 N.

2.4.6 (2009) Helmet-Systems Effects on Neck Muscle Demands

A biomechanics research group at the University of Waterloo was contracted by DRDC – Toronto to assess the effects of neck posture and helmet configuration on neck muscle demands. This project, as an exception, was not carried out to deliver a direct solution to neck strain. However, understanding the impact of helmet-systems on neck biomechanics allows for informed design of future helmet-systems and support devices. Experimentation was completed shortly after initiation in 2009, however the analysis of the data and subsequent final report was delivered in 2014 (Callaghan, 2014). Eight male subjects were each subjected to seven head/neck postures each under six helmet conditions. These seven head and neck postures in various and combinations of, degrees of motion: flexion, extension, lateral bend and axial twist. The postures were quasi-static, in which participants were instructed to slowly move towards the target posture, which was then sustained for 15 seconds. Thus, the investigators were mostly interested in isometric (static) contractions. The six helmet-system conditions were as follows: no helmet (control), helmet only, helmet with NVG down, helmet with NVG up, helmet with NVG down and counterweight, and helmet with NVG up and counterweight. Muscle activity was measured through electromyography (EMG) and head kinematics was captured through motion capture.

Kinematic results showed little variability within and between subjects, which verifies that postures were performed consistently and similar movement strategies were used. Neck strength data collected through MVC forces revealed differences primarily as a function of posture and exertion direction. The authors recommended that it would be beneficial for helmet-systems to avoid increased load moments in non-neutral postures, where strength was the weakest. Overall, EMG and kinematic data did not suggest any significant difference between helmet-system conditions. The authors hypothesized this lack of muscle response be attributed to the low velocity nature of the movements as this study was intentionally limited in scope to static holds. Thus, a recommendation was made for future research to examine dynamic neck movements, which are more typical of in-flight activities.

2.5 Post-2012 – Near-Term Solutions

2.5.1 Neck Strain Workshop

A Neck Strain Workshop was held in August 2012, hosted by DRDC and attended by DTAES, RMC, NRCC and Surgeon General, including academics from Queens University, University of Toronto and St. Michael’s hospital, as well as collaborators in industry. The workshop was convened to understand and coordinate seemingly isolated research efforts as well as accelerate efforts to produce actionable solutions for the RCAF. Also discussed were the benefits of a multidisciplinary approach to solving this multifactorial problem. The workshop produced the following statements:

The neck strain problem and contributing factors are sufficiently well understood to enable the pursuit of solutions;


The problem is multi-faceted, and so solutions must reduce causal factors on several fronts in order to reduce the incidence and severity of neck pain;

Complex biomechanical models are under development but are not going to provide results in the near and medium terms. However, simpler models can be used to support solutions in the timeframe; and

Neck strain continues to be highly prevalent in both fixed and rotary-wing aircrew due to the expectations that military aircrew will continue to wear head-supported mass.

Thus, decisions were made to consolidate all neck pain research funded by DND under a single project overseen by DRDC – Toronto. This project placed an emphasis on the design, development, and assessment of high ‘pay-off’ research and development that would deliver near- and mid-term mitigating strategies which reduce the incidence of aircrew neck pain.

2.5.2 Identification and Proposal of Near-Term Solutions

Flowing directly out of the Neck Strain Workshop, two contracts were concurrently let by DRDC – Toronto to Queen’s University (Fischer et al., 2013) and Toronto Research Institute (TRI) (Fernie & Mayich, 2013). The objective was to identify, through consultation with the operational community, cost-effective near term solutions that would address the most significant contributors to aircrew neck pain. The DRDC neck strain team subsequently analysed and prioritised the proposed solutions in terms of Effectiveness (the extent to which the solution reduces the risk of neck trouble), Level of Effort (needed to operationalise solution), and Timeliness (near-, mid-, or far-term solution) (Chafe, 2014). Figure 8 shows a list of compiled solutions from Queen’s University and TRI.

2.5.3 (03pg/13pg) Neck Strain Applied Research Project

DRDC – Toronto, in partnership with DTAES, Directorate of Air Requirements (DAR), Directorate of Air Programs and Surgeon General proposed an Applied Research Project (ARP), (03pg) Mitigating CF Helicopter Aircrew Helmet-Mass-Induced Neck Strain which addressed decisions flowing from the workshop (Goodman, 2013). The project sought to formally evaluate the most highly ranked near-term solutions as identified by Queen’s University (Fischer et al., 2013) and TRI (Fernie & Mayich, 2013). This ARP proposal was accepted, and work began in April 2013 under the DRDC Air Sustain Thrust project 13pg. During 13pg a NATO Human Factors Medicine (HFM) Exploratory Team (ET) 126 was formed entitled “Neck Pain Aircrew”, where Canada acted as the chair. The objective of the ET was to catalogue, from a NATO perspective, the prevalence of aircrew neck pain as well as any mitigating solutions adopted by nations. The international extent of aircrew neck strain saw HFM-ET-126 subsequently evolve into a three-year Research Task Group (RTG), becoming HFM-RTG-252.


. Figure 8: List of Proposed solutions from Toronto Rehabilitation Institute (TRI)

and Queen’s University (QU) (Chafe, 2014).

2.5.4 Neck- and Back-trouble Mitigating Solutions

Meanwhile, the DRDC as an agency underwent transformation of the science and technology (S&T) program formulation and delivery for the Canadian Armed Forces (CAF). A new (03aa) Air Human Effectiveness project charter (Horan & Farrell, 2014) was being developed where the Neck- and Back-trouble Mitigating Solutions Work Breakdown Element (WBE) was one of four WBEs within the project. The process of forming a new project should be seen as a continuation to the efforts and objectives outlined by 03pg/13pg ARP. This WBE represents the present basis at the time of this report. The scope of the WBE was subsequently redefined, which focuses on only neck trouble exclusively in CH-146 Griffon aircrew. Below lists the eight elements in the near-term solutions space currently under investigation:

1. Revised Workload Distribution and Smart Scheduling

2. Helmet Fit

3. ‘Professional Athlete’ mentality – Education and Exercise

4. Head-supported mass (HSM) Study

5. Helmet System Support Devices


6. Radar Altimeter Repeater Monitor

7. “See through floor” capability

8. Seat Ergonomics


3 Discussion

Through the presentation of the research chronology, it can be appreciated that the helicopter aircrew neck and back pain problem traces as far back as the emergence of rotary wing flight itself. An initial focus on pilot back pain saw the issue gain international precedence through first recognising the prevalence through surveys, subsequently leading to the initiation of formal research campaigns. Noteworthy is an Advisory Group for Aerospace Research and Development (AGARD) specialist’s meeting held in 1985 focusing on the aeromedical backache problem. It is this meeting which also highlights the invested Canadian research efforts from DCIEM amongst international collaborators (Beevis & Forshaw, 1985; Bowden, 1985; Landolt, 1985; van Vliet et al., 1985). Research topics spanned from problem definition, to understanding causal factors, to proposing mitigation solutions and strategies. Vibration and postural fatigue were identified as significant contributors to pilot backache. The back pain issue did not reach full resolution, as the 1990’s research reveals a shift of focus towards neck pain.

The sudden shift towards neck pain research flowing out of the 1990’s and extending to the present day may appear to coincide with the operationalisation of helmet-systems devices in the same time period. These events unfold in a similar manner as to the introduction of the helicopters as new technologies leading to back pain. The neck pain problem, however, should not be thought of as a new issue, as previous reports of back pain often also included neck pain (Delahaye et al., 1982). It is however, evident through the mounting research efforts that the neck pain problem had intensified beyond an insignificant level. It may thus be inferred that the induction of helmet-systems was a principal cause.

At the outset of the 2000’s a RCAF survey revealed the extent of aircrew neck pain, which was prevalent in over 80% of rotary wing aircrew (Adam, 2004). These findings galvanized an invested Canadian interest, which led to the initiation of multiple research campaigns. Almost identical in approach to that of the pilot backache problem in the 1980s, Canadian neck pain research spanned multiple fronts from exploring neck pain causality and mechanisms to mitigation solutions and strategies. However, with the occurrence of the Neck Strain Workshop in 2012 came a paradigm shift and a consequent shift in research focus. This shift resulted in the formulation of the current research program, which places an almost exclusive emphasis on delivering recommendations for near-term solutions which the RCAF may rapidly implement.

A gap analysis follows, which addresses research gaps within the scope of the report, specifically research conducted for the RCAF. It is recognized that other nations are similarly invested in the neck- and back- pain problem and may have studies relevant to the identified gaps.

The first gap, however, remains an open question amongst the international aeromedical community. That is, the underlying mechanism behind aircrew neck pain is still largely unknown. Although much of the modelling research in the 2000’s focussed on understanding neck pain mechanisms, a definitive pathology was never ascertained. Given knowledge of the specific neck-pain producing mechanism, solutions could be designed which target specific neck structures.

The second research gap departs from pain strictly experienced in the neck or back region. Recall that Canadian research on helicopter aircrew back pain never reached definitive solutions. The


2014 RCAF Survey clearly indicates that shoulder, upper back, and lower back pain continue to be a problem (Chafe & Farrell, 2016). Research pertaining to spinal pains, in general, may be viewed as research gaps. It is of note that, The Technical Cooperation Program (TTCP) Technical Panel 22 has a proposal to investigate aircrew spinal pain in 2016 (Shender, 2016).

The third research gap extends beyond neck and back pain only in the rotary wing. The historical review has revealed that Canadian research on aircrew neck and back pain has exclusively pertained to the rotary wing. The current DRDC neck trouble project focusses on CH-146 Griffon Helicopter aircrew. However, neck and back pain has been shown to be highly prevalent in other RCAF aircrew communities which include other rotary wing as well as fixed wing airframes (Hawes, Whitehead, & Gray, 2014). There are plans to conduct a survey for CF-188 aircrew to understand the neck pain prevalence in this community, and work towards solutions.

A fourth possible research gap is that neck, back and other spinal pain research approaches may extend to other components of the CAF to include the Royal Canadian Navy (RCN) and the Canadian Army (CA). For example, there have been past Canadian research efforts which examined the mass properties of infantry soldier headwear systems (Tack, Nakaza, McKee, MacEachern, & Marrao, 2006).

A cursory view of the historical review also lends to key lessons learned. One lesson learned is that developing solutions to this multi-faceted problem requires a multi-disciplinary team. In fact, all these expertise are needed to investigate this problem and develop solutions. None of these areas of research should be avoided. In fact, they form the basis for the neck pain causal factors as outlined by NATO RTG-HFM-252 and the current DRDC project (Farrell, Shender, & Fusina, draft):

Who aircrew are (i.e., human factors such as age, anthropometry, neck strength);

What aircrew wear (i.e., head- and neck-borne equipment);

What aircrew do (i.e., behaviours, tasks, and postures);

Where aircrew work (i.e., workspace ergonomics, vibration, and G forces); and

Why/when aircrew fly (i.e., organisation factors such as work-rest cycles, mission type/length).

A collaborative multi-disciplinary approach reveals the second lesson learned that oversight and integration are required to bring any research efforts, under a common goal. It is evident prior to the 2012 Neck Strain Workshop that neck pain research occurred independently of one another, and often each involved just one specific area of expertise. Such oversight would prevent the repetition of research efforts such as the case for neck finite element modelling through DTAES (Moglo et al., 2012) and DRDC – Toronto (Behdinan & Bahramsharhi, 2012a, 2012b) contracts.


4 Conclusions

A historical review of aircrew neck trouble research was conducted that focused on projects funded by various DND organizations. The main purpose of this review was to have a consolidated record of the DRDC research, from which one may note research areas to be avoided and those to be pursued. Lessons learned may be brought forward and applied to future research in related fields.

Chapter 2 contains a consolidated record of neck and back trouble related research extending back to the 1980s. It was found in the 1980’s that DCIEM (former DRDC – Toronto) undertook numerous research projects relating to pilot backache. After the 2000’s the research focus shifted to neck pain primarily caused by the induction of helmet-systems. The 2012 Neck Strain Workshop highlighted a paradigm shift towards rapid implementable solutions, which formed the foundation for the current DRDC neck strain project.

The research gaps gleaned from this historical review are as follows:

Understanding specific underlying mechanisms to aircrew neck and back trouble;

Research on other reported aircrew spinal trouble beyond neck and back;

Finding solutions for spinal trouble for other RCAF airframes; and

Finding solutions for spinal trouble for CA and RCN personnel who wear heavy helmet mounted systems.

Two key lessons are learned from this historical review:

Aircrew neck trouble is a multi-faceted problem requiring a multi-disciplinary research team; and

Oversight and integration are required to bring together the research and move decisively towards a solution(s).

It is hoped that this historical review provides a strong basis for building future research programs in this area that uses products from previous research, addresses research gaps, and implements lessons learned.


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List of Symbols/Abbreviations/Acronyms/Initialisms

ADM Assistant Deputy Minister

AGARD Advisory Group for Aerospace Research and Development

ALPHA Advanced Lightweight Protective Helmets for Aircrew

AO Atlanto-Occipital

APSC Aerospace Policy and Standards Committee

ARP Applied Research Project

ATVA Actively Tunable Vibration Absorber

BCC Braced Collar Concept

CA Canadian Army

CAF Canadian Armed Forces

CANDID Canadian Defence Information Database

CDU Control Display Unit

CFHS Canadian Forces Health Services

cm centimetres

CoM Centre of Mass

CTP Coordination Training Program

DAR Directorate of Air Requirements

DCIEM Defence and Civil Institute of Environmental Medicine

DND Department of National Defence

DRDC Defence Research and Development Canada

DTAES Directorate of Technical Airworthiness and Engineering Support

DTIC Defense Technical Information Center

EMG Electromyography

ESI Engineering Services Incorporated

ETP Endurance Training Program

FE Flight Engineer

HAC Helmet Attachment Concept

HCV Hooded Collar Vest

HFM Human Factors and Medicine

HMCS Helmet Mounted Cueing System


HMD Helmet Mounted Display

HSM Head Supported Mass

HUD Heads Up Display

Hz Hertz

IBC Individual Blade Control

IVD Intervertebral Disks

MVC Maximum Voluntary Contraction

NATO North Atlantic Treaty Organization

NDHQ National Defence Headquarters

NECSUS Neck Support System

NIRS Near Infrared Spectroscopy

NRCC National Research Council of Canada

NVG Night Vision Goggle

RCAF Royal Canadian Air Force

RCN Royal Canadian Navy

RMC Royal Military College

RTG Research Task Group

RTO Research and Technology Organisation

SAR Search and Rescue

SPH Sound Protective Helmet

TRI Toronto Rehabilitation Institute

TTCP The Technical Cooperation Program

UCR Unsatisfactory Condition Report

WBE Work Breakdown Element

WBV Whole Body Vibration

DOCUMENT CONTROL DATA (Security markings for the title, abstract and indexing annotation must be entered when the document is Classified or Designated)

1. ORIGINATOR (The name and address of the organization preparing the document. Organizations for whom the document was prepared, e.g., Centre sponsoring a contractor's report, or tasking agency, are entered in Section 8.) DRDC – Toronto Research Centre Defence Research and Development Canada 1133 Sheppard Avenue West P.O. Box 2000 Toronto, Ontario M3M 3B9 Canada

2a. SECURITY MARKING (Overall security marking of the document including special supplemental markings if applicable.)

UNCLASSIFIED

2b. CONTROLLED GOODS

(NON-CONTROLLED GOODS) DMC A REVIEW: GCEC DECEMBER 2013

3. TITLE (The complete document title as indicated on the title page. Its classification should be indicated by the appropriate abbreviation (S, C or U) in

parentheses after the title.) Royal Canadian Air Force Neck- and Back-Trouble Research : A Historical Review

4. AUTHORS (last name, followed by initials – ranks, titles, etc., not to be used) Xiao, A.; Farrell, P.S.E.

5. DATE OF PUBLICATION (Month and year of publication of document.) July 2016

6a. NO. OF PAGES (Total containing information, including Annexes, Appendices, etc.)

39

6b. NO. OF REFS (Total cited in document.)

63 7. DESCRIPTIVE NOTES (The category of the document, e.g., technical report, technical note or memorandum. If appropriate, enter the type of report,

e.g., interim, progress, summary, annual or final. Give the inclusive dates when a specific reporting period is covered.) Reference Document

8. SPONSORING ACTIVITY (The name of the department project office or laboratory sponsoring the research and development – include address.) DRDC – Toronto Research Centre Defence Research and Development Canada 1133 Sheppard Avenue West P.O. Box 2000 Toronto, Ontario M3M 3B9 Canada

9a. PROJECT OR GRANT NO. (If appropriate, the applicable research and development project or grant number under which the document was written. Please specify whether project or grant.)

9b. CONTRACT NO. (If appropriate, the applicable number under which the document was written.)

10a. ORIGINATOR’S DOCUMENT NUMBER (The official document number by which the document is identified by the originating activity. This number must be unique to this document.) DRDC-RDDC-2016-D031

10b. OTHER DOCUMENT NO(s). (Any other numbers which may be assigned this document either by the originator or by the sponsor.) 03aa

11. DOCUMENT AVAILABILITY (Any limitations on further dissemination of the document, other than those imposed by security classification.)

Unlimited

12. DOCUMENT ANNOUNCEMENT (Any limitation to the bibliographic announcement of this document. This will normally correspond to the Document Availability (11). However, where further distribution (beyond the audience specified in (11) is possible, a wider announcement audience may be selected.)) Unlimited

13. ABSTRACT (A brief and factual summary of the document. It may also appear elsewhere in the body of the document itself. It is highly desirable that the abstract of classified documents be unclassified. Each paragraph of the abstract shall begin with an indication of the security classification of the information in the paragraph (unless the document itself is unclassified) represented as (S), (C), (R), or (U). It is not necessary to include here abstracts in both official languages unless the text is bilingual.)

Griffon Helicopter aircrew neck trouble is likely to distract aircrew from performing flying tasks and, in the extreme, may cause them to be grounded. Rotary-wing aircrew back pain issues have been researched in the RCAF since the 1980’s, while neck pain came to the forefront in the 2000’s.

In cases of both neck and back trouble research, a number of Canadian research efforts were conducted ranging from understanding the problem to developing solutions. An effort to reinvigorate aircrew neck trouble research began after a 2012 Neck Strain Workshop, with a clear mandate to deliver solutions. This paper consolidates the research and studies that were performed for Royal Canadian Air Force (RCAF) on back and neck trouble leading up to current efforts. From this review, various research gaps and lessons learned are identified.

Research gaps include: a) investigating the underlying mechanisms to musculoskeletal neck pain, b) finding solutions for musculoskeletal trouble other than neck, and c) developing solutions to musculoskeletal trouble within rotary-wing, fast-jet, army and navy communities. Key lessons learned include: a) multi-faceted problems (such as neck-trouble amongst aircrew) require multi-disciplinary teams to understand the problem and develop solutions, and b) oversight helps align research to a central goal, which may be aided with use of a common conceptual framework.

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La douleur de cou qui est vécu par des membres d’équipage d’hélicoptère Griffon peut être distraire ces membres de l’exécution des tâches de vol et, à l’extrême, peut les causer à être mis à la terre. Les problèmes de la douleur de dos entre des membres d’équipage d’hélicoptère ont été étudiés dans l’Aviation royale canadienne (ARC) depuis les années 1980, alors que la douleur de cou est venue à l’avant-garde dans les années 2000.

Dans les cas des recherches sur des problèmes de cou et de dos, un certain nombre d’efforts de recherche canadiens ont été menées pour comprendre le problème et développer des solutions. Un effort pour relancer ces recherches la douleur au cou pour les équipages a commencé après une Atelier de 2012 sur ce sujet, avec un mandat clair pour offrir des solutions. Alors, ce document regroupe les recherches et les études qui ont été effectuées pour l’ARC sur le dos et le cou des problèmes jusqu’à efforts actuels. De cet examen, diverses lacunes de la recherche et les leçons apprises sont identifiés.

Les lacunes de la recherche comprennent: a) étudier les mécanismes fondamentaux de la douleur de cou musculo-squelettique, b) trouver des solutions pour des problèmes musculo-squelettique pour des autre parts de cours comme le dos, et c) développer des solutions à des problèmes musculo-squelettiques pour des autres hélicoptères, des rapide-jets, l’armée et la marine. Les leçons apprises comprennent: a) des problèmes à facettes multiples (comme la douleur de cou entre des membres d’équipage) ont besoin des équipes multidisciplinaires pour comprendre le problème et développer des solutions, et b) la surveillance permet d’aligner la recherche d’un objectif central, qui peut être aidé avec l’utilisation d’un cadre conceptuel commun.

14. KEYWORDS, DESCRIPTORS or IDENTIFIERS (Technically meaningful terms or short phrases that characterize a document and could be helpful in cataloguing the document. They should be selected so that no security classification is required. Identifiers, such as equipment model designation, trade name, military project code name, geographic location may also be included. If possible keywords should be selected from a published thesaurus, e.g., Thesaurus of Engineering and Scientific Terms (TEST) and that thesaurus identified. If it is not possible to select indexing terms which are Unclassified, the classification of each should be indicated as with the title.) neck pain; back pain; aircrew; CH-146 Griffon Helicopter; gap analysis; lessons learned; historical review

royal canadian air force neck- and back-trouble research · musculoskeletal trouble within...

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