dhc 8 ice shields

DHC-8 Ice Shields

Strength testing and repair studies,for the Widerøe airline.

Gisli Eiriksson

Hamza Alzubaidi

Supervisor

Paul Arentzen

This Bachelors Thesis is carried out as a part of the education at the University

of Agder and is therefore approved as a part of this education.

University of Agder, 2014

Faculty of Engineering and Science

Department of Engineering Sciences

Abstract

Widerøe is the largest regional airline in Scandinavia. It operates a fleet

of 42 Bombardier Dash-8 turbo-prop aircraft. Operating in the northern

hemisphere and at an altitude between 0 - 25.000 feet, the conditions for ice

are common. Ice contamination on a propeller will change the aerodynamic

characteristics of the Propeller. If the icing encounter is very severe the ice

catapulted from the propellers can dent the fuselage. A dent in the fuselage

caused by an object impacting it from the outside is very dangerous espe-

cially if it occurs in the pressurized area. To protect the aircrafts fuselage

an ice shield is mounted on the fuselage where the ice usually hits. Once hit

by ice the ice shields often have a somewhat reduced strength against new

ice impact. If such ice shields are not replaced, dents in the fuselage skin

may occur. Full strength ice shields are therefore essential in icy flight con-

ditions to avoid expensive subsequent repair work on the fuselage skin. This

report compares the strength of a new, repaired and damaged ice shields.

Investigates also the reparability of ice shields by assessing the potential of

original strength recovery.

To do the tests we constructed a mockup of an aircraft fuselage (AFM). We

fastened a 5.0 m long PVC pipe to a handrail in the mechatronics labora-

tory. The AFM was placed on the floor under the PVC pipe and the end of

the PVC pipe was directly over the measuring point on the AFM.

We used iron weights wrapped in padding and put them into 1/2 liter plastic

bottles and dropped them down the PVC pipe and measured the deforma-

tion that occurred on the AFM. From that we calculated the average impact

force exerted on the AFM.

From the results we concluded that a repaired ice shield will have equal or

more strength than a new one. The original strength recovery of a damaged

ice shield can be obtained by following the repair procedures.

i

Contents

1 Introduction 1

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

1.2 Icing on Aircrafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2.1 Ice Contamination on Wings . . . . . . . . . . . . . . . . . . 2

1.2.2 Ice Contamination on Propellers . . . . . . . . . . . . . . . . 3

1.3 The Purpose of Ice Shields . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 Research Question . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Methodology 5

2.1 Measurement Methods . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.1 Water Indicator . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.2 Strain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.3 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . 7

2.1.4 Piston / Telescoping Test . . . . . . . . . . . . . . . . . . . 8

2.2 Simulating Ice Impact . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2.1 Pendulum Test . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2.2 Dropping a Known Mass from a Known Height . . . . . . . 9

3 Procedures 9

3.1 Ice Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1.1 Repair Procedures . . . . . . . . . . . . . . . . . . . . . . . 9

3.2 Fuselage Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.3 Reliabilty Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.3.1 Height Reliability Test . . . . . . . . . . . . . . . . . . . . . 11

3.3.2 AFM Reliability Test . . . . . . . . . . . . . . . . . . . . . . 12

3.4 Foam Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.5 Density of Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.6 The Impact Force Experiment . . . . . . . . . . . . . . . . . . . . . 15

4 Results 19

4.1 Dropping of Weights . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.2 New Compared to Damaged Ice Shield . . . . . . . . . . . . . . . . 20

4.3 New Compared to Repaired Ice Shield . . . . . . . . . . . . . . . . 22

ii

4.4 Foam Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4.1 New Ice Shield . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.4.2 Damaged Ice Shield . . . . . . . . . . . . . . . . . . . . . . . 26

4.4.3 Repaired Ice Shield . . . . . . . . . . . . . . . . . . . . . . . 28

4.5 Impact Force Compared to Kinetic Energy . . . . . . . . . . . . . . 30

4.6 Three Point Flexure Test . . . . . . . . . . . . . . . . . . . . . . . . 31

5 Discussion 32

5.1 Strength Comparison of Ice Shields . . . . . . . . . . . . . . . . . . 32

5.1.1 Remaining Strength of Damaged Ice Shield . . . . . . . . . . 32

5.1.2 Remaining Strength of Repaired Ice Shield . . . . . . . . . . 33

5.2 Comparison of Foam . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.3 Economical Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6 Conclusion 34

6.1 Recommendation for Further Research . . . . . . . . . . . . . . . . 35

References 36

Appendices 38

iii

List of Figures

1 Ice Accumulation on Aircrafts per Hour . . . . . . . . . . . . . . . . 1

2 Propeller Electric Heating Element . . . . . . . . . . . . . . . . . . 3

3 Ice Shield on an Aircraft . . . . . . . . . . . . . . . . . . . . . . . . 4

4 Function Meens Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5 Water Indicator on the AFM . . . . . . . . . . . . . . . . . . . . . . 6

6 Strain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . . . . . 7

8 Telescoping Curtain Rod . . . . . . . . . . . . . . . . . . . . . . . . 8

9 Dent Repairs from Ice Impact on an Aircraft . . . . . . . . . . . . . 10

10 A Hole in the AFM after a Test Drop . . . . . . . . . . . . . . . . . 12

11 The Impact Force Experiment . . . . . . . . . . . . . . . . . . . . . 15

12 Graph of New Ice Shield Compared to Damaged One with Different

Masses Dropped from a Height of 5.02 m . . . . . . . . . . . . . . . 20

13 Graph of New Ice Shield Compared to Repaired One with Different

Masses Dropped from a Height of 5.02 m . . . . . . . . . . . . . . . 22

14 Graph of New Ice Shield where New, Damaged and Double Foam

are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

15 Graph of Damaged Ice Shield where New, Damaged and Double

Foam are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . 26

16 Graph of Repaired Ice Shield were New, Damaged and Double Foam

are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

17 Graph Comparing Strength of New, Damaged and Repaired Ice Shield 30

18 Three Point Flexure Test Data . . . . . . . . . . . . . . . . . . . . 31

iv

List of Tables

1 Kinetic Energy of Ice Particles Hitting The Ice Shield . . . . . . . . 17

2 Mass for Equivalent Kinetic Energy . . . . . . . . . . . . . . . . . . 17

3 Kinetic Energy of Weights . . . . . . . . . . . . . . . . . . . . . . . 18

4 Mass for Equivalent Kinetic Energy . . . . . . . . . . . . . . . . . . 18

5 Table of New Ice Shield where New, Damaged and Double Foam

are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6 Table of Damaged Ice Shield where New, Damaged and Double

Foam are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . 27

7 Graph of Repaired Ice Shield were New, Damaged and Double Foam

are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . . . . . 31

v

List of Symbols

Symbol Meaning

Ek Kinetic Energy [Joules]

Ep Potential Energy [Joules]

F Force [Newton]

g Gravitational Acceleration [m/s2]

h Height [m]

J Joule

m Mass [kg]

r Radius [m]

s Deformation [mm]

V Volume [m3]

Vice Volume of Ice [m3]

Vimp Impact Velocity [m/s]

Vtip Propeller Blade Tip Velocity [m/s]

Vwater Volume of Water [m3]

ω Angular Velocity

ρ Density [kg/m3]

π Pi

List of Abbreviations

Abbreviation Meaning

AFM Aircraft Fuselage Mockup

AIF Average Impact Force [Newton]

MDF Medium-Density Fibreboard

PVC Polyvinyl Chloride

rpm Revolutions Per Minute

vi

Preface

It is with excitement and little sadness that we finish our third and final year

as aeronautical engineering students. We chose to do a bachelor project for the

Widerøe airline because we wanted to solve a real problem on a real aircrafts. The

last five months have been really interesting, educational and sometimes difficult.

It has been fantastic to work with the Widerøe airline on this project. The pinna-

cle moment was when we were invited by Widerøe to Bodø. We spent two whole

days with Geir Johnny Karlsen, one of Widerøe‘s aeronautical engineers where he

helped us find essential information for the project. There we also had the op-

portunity to talk to all of the fantastic people who operate and repair the DHC-8

aircrafts. We got a much deeper understanding of the ice shield problem and the

operation of the DHC-8 aircrafts.

We would like to thank the whole staff at Widerøe airlines for being so willing and

enthusiastic to answer all our questions and for inviting us to Bodø, to experience

a day in an aeronautical engineer‘s life.

We would also like to thank all the personal at the mechatronic and construction

laboratories at UIA.

We would like to give a special thanks to Geir Johnny Karlsen for creating this

project and for helping us through the whole project.

Last but not least we would like to thank our supervisor Paul Arentzen for helping

us through problems and finding solutions.

Hamza Alzubaidi Gisli Eiriksson

vii

1 Introduction

1.1 Background

Widerøe is the largest regional airline in Scandinavia and operates more than 450

flights every day. In Norway the airline fly’s to more than twice as many airports

than any other airline. Widerøe operates a fleet of 42 Bombardier Dash-8 turbo-

prop aircraft previously known as the de Havilland Canada Dash 8 or DHC-8.

The fleet consists of 20 DHC-8 100, 3 DHC-8 Q200, 8 DHC-8 300 and 11 DHC-8

Q400 aircrafts. All the aircrafts are built between 1990 and 2010. Operating in

the northern hemisphere and at an altitude between 0 - 25.000 feet the conditions

for ice are common.[16][17]

1.2 Icing on Aircrafts

Figure 1: Ice Accumulation on Aircrafts per Hour

1

The maximum operating altitude for the 100 - 300 series is 25.000 feet and 27.000

feet for the 400 series. Below−10o C the icing conditions are usually not very severe

however between 0o C and −10o C most ice contamination occurs.[3] Accumulation

of ice on an aircraft can seriously change its aerodynamics and cause problems and

even lead to crashes. The intensity of ice accretion on an aircraft can be light,

moderate and severe. Light icing does not pose any specific restraints on the

behavior of the aircraft. Light icing is defined as more than 10 kg/m2 of ice

an hour. Moderate icing conditions may cause the crew to change heading or

altitude. Moderate icing is defined as more than 60 kg/m2 of ice an hour. Severe

icing conditions which force the crew to immediately change heading or altitude.

Severe icing is defined as more than 120 kg/m2 of ice an hour as seen on Figure

1.[4]

1.2.1 Ice Contamination on Wings

Ice contamination on a wing will change the aerodynamic characteristics of the

wing. It will stall at a lower angle of attack and higher speed. Serious roll control

problems are also not unusual. Even small amounts of ice will have an effect, and

if the ice is rough, it can be a large effect. To clear the ice of the wings of DHC-8

aircrafts a rubber deicing boot is inflated with air, producing ridges to crack and

dislodge any accumulated ice.[11]

2

1.2.2 Ice Contamination on Propellers

Figure 2: Propeller Elec-

tric Heating Element

Ice contamination on a propeller will also change

its aerodynamic characteristics. A propeller is basi-

cally a rotating wing. Ice accretion on the propeller

causes higher engine power requirement for a given

airspeed. To economize electrical power, usually two

propeller blades are de-iced at a time. A heat is ap-

plied to the blades for 10 - 20 seconds followed by a

60 seconds off period. If the icing encounter is very

severe, ice can accumulate on the propeller blades

during the 60 seconds off time. This can cause ice

to shed and impact the fuselage. Propellers are usu-

ally protected only up to 25-30 % of the propeller

disc radius. The reason is that the high velocity of

the propeller blade tip will usually avoid ice forma-

tion, and that centrifugal force will usually cause ice

shedding. Due to very low temperatures at higher

altitudes, ice can accumulate also on the tip. To

clear the ice off the propellers of DHC-8 aircrafts a

de-icing electric heating element is mounted on part

of the leading edge on the propeller blades as seen on Figure 2.[5] The propeller

de-icing system has three selections, off, above −10o C and below −10o C. Each

on timer provides four sequential outputs of either of two frequency cycles depend-

ing on the outside air temperature. Control switch selection of ABOVE −10o C

provides a timer frequency of 10 seconds control power activation followed by a 60

second dwell time. Control switch selection of BELOW −10o C provides timer fre-

quency of 20 seconds control power activation followed by a 60 second dwell time.

In icing conditions the pilots increase the rpm of the propellers both to increase

the airspeed of the aircraft and the centrifugal force on the propeller blades to get

rid of the ice contamination.[Reference... Ice and Rain protection]

3

1.3 The Purpose of Ice Shields

Figure 3: Ice Shield on an Aircraft

When flying in icy conditions, heat

is applied to the propeller blades for

de-icing. The ice that breaks loose

from the rotating propellers is cat-

apulted at a very high speed and

some will hit the fuselage. Without

protection their impact could dam-

age the fuselage skin. To protect

the aircrafts fuselage an ice shield is

mounted on the fuselage where the

ice usually hits. The main purpose

is to absorb most of the energy from

the incoming ice as seen on Figure

3. The ice shield is a glass and Aramid fiber epoxy composite panel covering a

thin foam rubber pad back side.

Once hit by ice the ice shields often have a somewhat reduced strength against

new ice impact. If such ice shields are not replaced, dents in the fuselage skin may

occur. Full strength ice shields are therefore essential in icy flight conditions to

avoid expensive subsequent repair work on the fuselage skin.

1.4 Research Question

Compare strength of a new, repaired and damaged ice shield, examine the degree

of damage and find out how much ice-protection they provide the fuselage. Also

investigate the reparability of an ice shield by assessing the potential of original

strength recovery.

4

2 Methodology

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Figure 4: Function Meens Tree

5

2.1 Measurement Methods

Aircraft fuselage mockup (AFM) is a fuselage simulator that we constructed to

mount the ice shield and the measuring equipment on. We constructed the AFM

from wooden materials, MDF sheets and plywood. The structure was made air-

tight in order to use water indicator as a measurement equipment.

2.1.1 Water Indicator

Figure 5: Water Indicator on the AFM

A hose is mounted through a hole in the airtight AFM structure. It forms a U

shape on the sidewall and is filled halfway with water as seen on Figure 5. When

the impact happens the water should rise since the structure is airtight, and it

should indicate the displacement transferred through the ice shield.

In theory this method should work fine, but in reality it did not. It did not give

the expected indication. We concluded that the volume/deformation ratio was too

low. The water level rose only about 1.0 mm and that was way too little.

6

2.1.2 Strain Gauge

Figure 6: Strain Gauge

A strain gauge was glued to the upper

surface of the curved plywood sheet, and

another to the bottom surface as seen in

Figure 6.

We found out when we started testing

that strain gauges give unreliable mea-

surements when mounted on wood, and

when measuring impact forces.

2.1.3 Three Point Flexural Test

Figure 7: Three Point

Flexural Test

This test was to compare the force needed to

deform ice shields in different conditions, new,

damaged and repaired. It was used to con-

firm how precise our measurements were in the

impact force experiment and if they were reli-

able.

It was clarified that our project does not involve

bending test, and that is why we could not rely on it

as a main test method. The machine used to test the

ice shield is Si Plan universal test machine [A2]. We

cut the ice shield in small specimens that are 0.13 m

long and 0.05 m wide. The specimens were placed

on two iron block supports that were 0.08 m apart, a

loading actuator applies the load exactly in the middle of the ice shield specimens

as seen on Figure 7.

7

2.1.4 Piston / Telescoping Test

Figure 8: Telescoping Curtain Rod

We thought of using some mechanical device in order to measure the deformation

of the AFM. We decided to use an adjustable curtain rod as seen on Figure 8. It

was fasten beneath the thin curved plywood sheet on the AFM. A plastic strip

was mounted on the adjustable curtain rod. When the impact occurred the plastic

strip indicated how much deformation the ice shield experienced during the im-

pact. The deformation was measured with a caliper.

This method worked out to be the most precise way to measure deformation using

the AFM. We continued testing using this method and got useful, comparable

results.

2.2 Simulating Ice Impact

2.2.1 Pendulum Test

A pendulum would hold weights at the end of an arm. A rope would be used to

pull the arm up. When the accurate height is accomplished the rope would be

released. The mass at the end of the arm would hit the ice shield which would be

mounted on the AFM.

8

2.2.2 Dropping a Known Mass from a Known Height

In order to perform a test with any of the measurements mentioned in chapter

2 an ice impact simulator needed to be used. The best way to do that with the

lowest fail margin was to drop an ice from a known height. To hit the ice shield at

the same place all the time a straight PVC pipe was used. The chosen PVC pipe

was 5.0 m long with a diameter of 70 mm as seen on Figure 11.

We chose this method because it is simple, cheap and easy to construct and deal

with.

3 Procedures

3.1 Ice Shield

The ice shield is built up of six fiber layer composites that are 1.12 mm thick, and

a foam rubber pad that is 3.18 mm thick. The outer layers are Cloth-Glass epoxy

pre-impregnated fibers. The inner layers are four layers of Cloth-Aramid Fabric

epoxy pre-impregnated fibers. [A3]

The weight of a new ice shield is about 7 kg while the weight of a repaired ice

shield can be as much as 17 kg. The usual lifetime of a new ice shield is estimated

to be 10 - 15 years, before it has to be repaired due to ice impact damage.[9]

When the ice shield is damaged the next impact can dent the fuselage, because

the remaining strength is impaired.

Damage detection is done by visual control each time the aircraft undergoes an A-

check. A damaged ice shield will be repaired if it has crack or puncture damage[2].

Each type of damage has a specific repair manual that has to be followed in order

to be approved.[A6][A7][A8][A9]

3.1.1 Repair Procedures

There are several types of ice shields that are in use depending on the DHC-8

series. Each of them has their own specific repair drawing that has to be followed

9

in order to repair any type of damage. A manual specifies a repair procedure for

crack and puncture damage.[A6][A7][A8][A9].

When damage can not be identified by the repair drawing, the repair has to be

approved by Bombardier. This procedure costs 500 - 2 000 USD(2 977 - 11 908

NOK, 20/05/2014).[1][9]

When a repair is done, the next step is to paint the ice shield. The paint provides

protection from corrosion, sunlight and moisture. Aramid fibers are weak against

sunlight and moisture.[9] A paint job for a new ice shield costs 5 000 - 5 500 NOK

and for a repaired one 17 000 - 18 000 NOK. The paint procedure can be found in

Appendix A4.[12]

3.2 Fuselage Damage

Figure 9: Dent Repairs from Ice Impact on an Aircraft

10

The fuselage is the main body of an aircraft, and it is a support structure. A dent

in the fuselage caused by an object impacting it from the outside is very dangerous

especially if it occurs in the pressurized area. If the fuselage skin dents inward, it

will bounce out when the cabin pressure is turned on. It bounces back in when

the cabin pressure is turned off. This will cause metal fatigue in the fuselage skin,

and it will definitely become a crack if nothing is done.

Dents in the fuselage pressurized area cannot be more than 0.20 mm in depth.[9]

The repair procedure of a dent in the fuselage is to cut out the surrounding area

of the dent. Then applying doubler over the cut out area as seen on Figure 9.

The stringers surrounding the cut out has to be replaced also.[14] This procedure

is expensive and takes a lot of time, which means the aircraft has to be grounded

which is very costly.

3.3 Reliabilty Tests

3.3.1 Height Reliability Test

To make sure that the test method described in chapter 2.2.2 was reliable, a

reliability test was done. In theory a specific mass dropped from 5.02 m should

have the same kinetic energy as a much smaller mass traveling at higher speed.

To test this theory we dropped a 0.109 kg weight from a height of 5.02 m and got

elastic deformation of 14.5 mm on the AFM. The energy from a 0.109 kg weight

dropped from a height of 5.02 m is equal to:

Ep = mgh = 0.109 kg·9.81 m/s2 · 5.02 m = 5.37 Joule.

Average impact force times deformation is equal to change in kinetic energy

AIF= Ek

s

The impact force will then be AIF= Ep

s= 5.37J

0.0145m= 370.3 N

Next we dropped a 0.544 kg weight from a height of 1.04 m and we got a defor-

mation of 14.5 mm. We calculate the same as before:

Ep = mgh = 0.544 kg ·9.81 m/s2 · 1.04 m = 5.55 Joule.

11

The impact force will then be AIF= Ep

s= 5.55J

0.0155m= 358.1 N

The difference in impact force is only ∆AIF = (370.3N−358.1N)370.3N

= 0.0329 = 3.3 %

The reason for this difference is because we should have gotten the same potential

energy Ep but these weights were the closest we could get. To get the same Ep

the weight dropped from 1.04 m should have been:

m = Ep

gh= 5.37J

9.81m/s2∗1.04m = 0.526 kg

The difference in mass from what the heavier weight should have been (0.526 kg)

and what it actually was (0.544 kg) is:

∆m = (0.544kg−0.526kg)0.544kg

= 0.033 = 3.3 %

This test concluded that the implemented method is reliable and can simulate the

kinetic energy ice particles could have when they hit the ice shield.

3.3.2 AFM Reliability Test

Figure 10: A Hole in the AFM af-

ter a Test Drop

After some tests with the ice shield

mounted on the (AFM) we wanted to

check out if the ice shield was actu-

ally absorbing most of the energy from

the impact. We decided to take the

ice shield of the AFM and test the

AFM without it as seen on Figure

11.

We decided to do a test drop with a mass of

1.549 kg drop it from 5.02 m, because that

was the heaviest mass that we were going

to use in the experiment. It went straight

through the AFM as seen on Figure 10. That concluded that the ice shield is

absorbing most of the impact force and therefore protecting the fuselage.

12

3.4 Foam Test

The painting procedure may affect the foam rubber pad as the last step in the

painting process is to dry the paint in an oven for one hour at 60o C. We did some

research and found out that the operating temperature for this foam material is

from −73o C to 260o C.[13]

But even though we decided to test if the paint procedure could affect the foam. We

heated a piece of foam for one hour at 60o C. There was no change in the material

after heating it. We measured the difference between unheated and heated foam

and could not find any differences.

3.5 Density of Ice

Ice frozen at atmospheric pressure is approximately 8.3 % less dense than liquid

water. The density of ice is 916.7 kg/m3 at 0o C, whereas water has a density of

999.8 kg/m3 at the same temperature. Liquid water is densest, essentially 1000

kg/m3, at 4o C and becomes less dense as the water molecules begin to form the

hexagonal crystals of ice as the freezing point is reached. This is due to hydro-

gen bonding dominating the intermolecular forces, which results in a packing of

molecules less compact in the solid. Density of ice increases slightly with decreasing

temperature and has a value of 934.0 kg/m3 at -180 o C at atmospheric pressure.

However ice gets less dense at high altitude because of low pressure.[?]

Because of the different density of ice at different pressure we did our own density

test of the ice that we used in the experiment. First we pored 1.0 kg of water in a

plastic bag and put in the freezer over night. Then we used a big pot and filled it

half way up with water, thereafter we put the frozen 1 liter ice bag and submerged

it in the water and measured the water displacement. The water displacement was

18 mm.

Volume of a cylinder V = πr2h

Radius of the pot = 0.14 m

13

Vice = πr2h = π · (0.14 m)2 · 0.018 m= 1.108 · 10−3 m3

Vwater = 1.0 · 10−3 m3

∆V = (1.108·10−3m3−1.0·10−3m3)1.0·10−3m3 = 0.108 = 10.8 %

The ice has 10.8 % more volume than water. Then the density is equal to:

ρice == kgm3 = 1.0kg

1.108·10−3m3 = 902 kg/m3

The ice that we will use in our experiment will have density of 902 kg/m3.

14

3.6 The Impact Force Experiment

Figure 11: The Impact Force Ex-

periment

After constructing the AFM and choos-

ing the best measuring method we started

to put everything in the right place for

the impact force experiment. We used

the impact method described in chap-

ter 2.2.2. We fastened the 5.0 m

long PVC pipe to a handrail in the

mechatronics laboratory. The AFM was

placed on the floor under the PVC pipe

and the end of the PVC pipe was di-

rectly over the measuring point on the

AFM.

The measuring device described in chapter

2.1.4 was used. The ice shield was mounted

on the AFM and the PVC pipe was 30 - 40

mm over it.

To make the simulation as real as possi-

ble we used frozen ice blocks with different

mass. For each test we melted and cut the

ice blocks to the right size and mass. We

dropped ice blocks with mass of 0.660 kg,

1.32 kg and 1.98 kg. These masses dropped

from a height of 5.0 m resemble the kinetic

energy from an ice particles of 2.0 · 10−3 kg,

4.0·10−3 kg and 6.0·10−3 kg catapulted from

the propeller at a speed of 178 m/s. For the

1.98 kg ice test we had to use a combination

of ice block and an iron weight because otherwise the ice block would have to be

0.60 - 0.70 m long.

15

We dropped the ice blocks down through the PVC pipe and then measured the

deformation registered with the telescoping curtain rod. It worked fine for a while

but we encountered a problem with the ice and iron weight combination. Some-

times the ice fell before the iron weight. We also noticed that some of the ice blocks

smashed into small pieces and other did not. After close examination we found out

that some ice blocks had many cracks in them after freezing and other had almost

no cracks. The measurements were not accurate because of this problem. The ice

blocks that had many cracks absorbed more energy during the impact than the

ice blocks that did not have any cracks prior to the drop. We also encountered a

problem with the mass of the ice blocks. It was difficult to get the mass exactly

right all the time. It was concluded that we should abort this method and find

another.

We had to find a way to keep the mass constant always. By putting iron weights

wrapped in padding into 1/2 liter plastic bottles we accomplished that. The masses

we used in this experiment were 0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370

kg. This method worked really well. All the results we got looked similar. Except

for the 1.549 kg then the results started to look funny and with the 2.370 kg the

AFM broke. The plywood started to crack and delaminate so we stopped the

experiment. We had already gotten all the measurements needed.

The size and mass of the ice particles that are catapulted from the propeller blades

differ a lot. In this experiment we were going to simulate an ice mass of 10.0 ·10−3

kg, 50.0 · 10−3 kg and 100.0 · 10−3 kg. The rotational speed of the propeller we

decided to set to 850 rpm. That is the normal rotational speed of the DHC-

8 aircraft propellers at cruising speed. To find out how much energy those ice

particles have when they hit the ice shield, we first needed to find the propeller

blade tip speed. The diameter of the propellers on the DHC-8 is 4 m. Most ice

particles are catapulted from the propeller blade tip because of centrifugal force

and therefore we use the propeller blade tip velocity for all our calculations.

Vtip = r2πω = 22 · π · 850rpm60s

=178 m/s

We anticipate that the ice particles have that speed when they hit the ice shield.

The kinetic energy that the ice particles have is then:

16

Ek = 12m(Vtip)

2

Table 1: Kinetic Energy of Ice Particles Hitting The Ice Shield

Mass [kg] Vtip [m/s] Ek [J]

0.01 178 158.4

0.05 178 792.1

0.1 178 1584.2

To find out how much mass we had to drop from 5.02 m to get the equivalent

kinetic energy from the ice blocks we first had to find the impact velocity:

Ek = Ep => 12m(Vimp)

2 = mgh => Vimp =√

2gh

Vimp =√

2 · 9.81m/s · 5.02m = 9.92 m/s

Calculation of the mass for the equivalent kinetic energy:

Ek = 12m(Vimp)

2 => m = 2·Ek

(Vimp)2

Table 2: Mass for Equivalent Kinetic Energy

Ek [J] Vimp [m/s] Mass [kg]

158.4 9.92 3.2

792.1 9.92 16.1

1584.2 9.92 32.2

From these calculations as seen in Table 2 it became obvious to us that we had to

simulate much smaller ice particles than 10.0·10−3 kg, 50.0·10−3 kg and 100.0·10−3

kg. The AFM could never handle this kind of impact force from these masses. We

decided then to simulate an ice mass in the range of 1.0 to 10.0 · 10−3 kg.

The masses we used in this experiment were 0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg

and 2.370 kg. The kinetic energy from them is then as seen in Table 3:

17

Table 3: Kinetic Energy of Weights

Mass [kg] Vimp [m/s] Ek [J]

0.339 9.92 16.7

0.664 9.92 32.7

1.380 9.92 67.9

1.549 9.92 76.2

2.370 9.92 116.6

Ek(weights) = 12m(Vimp)

2

Then we find out how much mass the ice particles has to have if it is traveling at

a speed of 178 m/s, we calculate:

Ek = 12m(Vtip)

2 => m = 2Ek

(Vtip)2

Table 4: Mass for Equivalent Kinetic Energy

Ek [J] Vimp [m/s] Mass [kg]

16.7 178 1.05 · 10−3

32.7 178 2.06 · 10−3

67.9 178 4.28 · 10−3

76.2 178 4.81 · 10−3

116.6 178 7.36 · 10−3

From these calculations we see in Table 4 that our simulation with masses of 0.339

kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370 kg dropped from a height of 5.02 m

have the equivalent kinetic energy as ice particles traveling at a speed of 178 m/s

and with masses 1.05 · 10−3 kg, 2.06 · 10−3 kg, 4.29 · 10−3 kg, 4.81 · 10−3 kg and

7.36 · 10−3 kg.

The average impact force (AIF) exerted on the AFM is then:[6]

18

AIF(0.339kg) = Ek

s= 16.68J

0.017m= 981 N

All the AIF and the deformations results are shown in tables in chapter 4.

4 Results

4.1 Dropping of Weights

As explained in chapter 3.6 we used iron weights wrapped in padding and put

them into 1/2 liter plastic bottles to get constant mass. The masses we used was

0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370 kg. In the following sub chapters

we will study results from each mass on new, damaged and repaired ice shield. We

will also compare new, damaged and double foam.

19

4.2 New Compared to Damaged Ice Shield

Damaged Ice Shield

New Ice Shield

Damaged Ice Shield

New Ice Shield

Damaged Ice Shield

New Ice Shield

New Ice Shield

Damaged Ice Shield

950

1150

1350

1550

1750

1950

2150

15 20 25 30 35 40 45 50

Impa

ct F

orce

[N]

Deformation [mm]

New vs Damaged Ice Shield

0.339 kg

0.684 kg

1.380 kg

1.549 kg

Figure 12: Graph of New Ice Shield Compared to Damaged One with Different

Masses Dropped from a Height of 5.02 m

On the graph on Figure 12 we compare new and damaged ice shield. We examine

them under different impact force conditions. We begin with 0.339 kg. The im-

pact force difference is ∆AIF = (1076N−981N)981N

· 100 = 9.7 %. A damaged ice shield

20

transfers 9.70 % more impact force to the AFM than a new one.

The next mass is 0.684 kg. The difference between new and damaged ice shield is

0.86 % where the new ice shield is better.

The next mass is 1.380 kg. The difference between new and damaged ice shield is


The last mass is 1.549 kg. The difference between new and damaged ice shield is

11.52 % where the damaged ice shield is better. Here the results are opposite to

the other masses and as explained in chapter 5.1.1 the results from 1.549 kg where

unreliable.

21

4.3 New Compared to Repaired Ice Shield

New Ice Shield

Repaired Ice Shield

Repaired Ice Shield

New Ice Shield

Repaired Ice Shield

New Ice Shield

Repaired Ice Shield

New Ice Shield

900

1100

1300

1500

1700

1900

2100

15 20 25 30 35 40 45 50

Impa

ct F

orce

[N]

Deformation [mm]

New vs Repaired Ice Shield

0.339 kg

0.684 kg

1.380 kg

1.549 kg

Figure 13: Graph of New Ice Shield Compared to Repaired One with Different

Masses Dropped from a Height of 5.02 m

On the graph on Figure 13 we compare new and repaired ice shield. We examine

them under different impact force conditions. We begin with 0.339 kg. The impact

force difference is ∆AIF = (981N−927N)927N

· 100 = 5.80 %. A new ice shield transfers

5.80 % more impact force to the AFM than a repaired one.

22

The next mass is 0.684 kg. The difference between new and repaired ice shield is

1.24 % where the repaired ice shield is better.

The next mass is 1.380 kg. The difference between new and repaired ice shield is

4.52 % where the repaired ice shield is better.

The last mass is 1.549 kg. The difference between new and repaired ice shield is


4.4 Foam Comparison

On the graphs on Figures 14, 15 and 16 we compare new, damaged and double

foam on a new, damaged and repaired ice shields. We examine them under different

impact force conditions.

23

4.4.1 New Ice Shield

Damaged Foam

New and Double Foam

Damaged Foam

New Foam

Double Foam

Damaged Foam

New an Double Foam

New, Damaged and Double Foam

970

1170

1370

1570

1770

1970

2170

2370

16 21 26 31 36 41 46 51

Impa

ct F

orce

[N]

Deformation [mm]

New Ice Shield

0.339 kg

0.684 kg

1.380 kg

1.549 kg

Figure 14: Graph of New Ice Shield where New, Damaged and Double Foam are

Compared

24

Table 5: Table of New Ice Shield where New, Damaged and Double Foam are

Compared

AIF (N) = Avg. impact force in newtons

New Ice Shield Impact velocity = 9.9 m/s

0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)

Foam/Weight (mm) AIF (N) (mm) AIF (N) (mm) AIF (N) (mm) AIF (N)

Damaged Foam 17 981 22.5 1496 31.5 2155 40 1905

New Foam 17 981 24.2 1390 33 2057 43.5 1752

Double Foam 17 981 24.2 1390 33 2057 45.5 1675

On the graph on Figure 14 we compare new, damaged and double foam on a new

ice shield. We begin with 0.339 kg. The impact force is the same for all types

of foam i.e. 981 N. The next mass is 0.684 kg. The difference between new and

double foam is nothing. Between damaged foam and, new and double foam is

∆AIF = (1496N−1390N)1390N

· 100 = 7.6 %. The mass of 0.684 kg exerts 7.6 % more

impact force on the AFM when a new ice shield has a damaged foam than if it

has new or double foam.

The next mass is 1.380 kg. The difference between new and double foam is also

nothing. Between damaged foam and, new and double foam the difference is 4.8

%. The mass of 1.380 kg exerts 4.8 % more impact force on the AFM when the

ice shield has a damaged foam than if it has new or double foam.

The last mass is 1.549 kg. The difference between new and double foam is 4.6 %

where the new foam is worse. However the difference between damaged foam and

double foam is 3.7 %. The mass of 1.549 kg exerts 13.7 % more impact force on

the AFM when a new ice shield has a damaged foam than if it has double foam

and that is significant difference.

25

4.4.2 Damaged Ice Shield

Damaged Foam Double Foam

New Foam

New Foam

Damaged Foam

Double Foam New Foam Double Foam Damaged Foam

Damaged Foam

New Foam Double Foam 970

1170

1370

1570

1770

1970

2170

15 20 25 30 35 40 45 50 55

Impa

ct F

orce

[N]

Deformation [mm]

Damaged Ice Shield

0.339 kg

0.684 kg

1.380 kg

1.549 kg

Figure 15: Graph of Damaged Ice Shield where New, Damaged and Double Foam

are Compared

26

Table 6: Table of Damaged Ice Shield where New, Damaged and Double Foam

are Compared


Damaged Ice Shield Impact velocity = 9.9 m/s

0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)


Damaged Foam 15.5 1076 24 1402 31 2190 49 1555

New Foam 16.5 1011 23 1463 33 2057 42.5 1793

Double Foam 17 981 23.5 1432 31.5 2155 52 1465

For the graph on Figure 15 we do the same comparison as in the previous chapter

but now with damaged ice shield. We begin with 0.339 kg. The impact force with

damaged foam is ∆AIF = (1076N−981N)981N

· 100 = 9.7 % higher than with double

foam i.e. 1076 N compared to 981 N. With new foam the mass exerts 3.1 % more

impact force on the AFM than with double foam.

The next mass is 0.684 kg. The difference between new and damaged foam is 4.4

% where the new foam is worse. The double foam exerts 2.1 % more impact force

on the AFM than the damaged foam.

The next mass is 1.380 kg. The difference between new and double foam is 4.8 %.

Damaged ice shield with double foam exerts 4.8 % more impact force on the AFM

than damaged ice shield with new foam. However the difference between damaged

foam and new foam is 6.5 %. The mass of 1.380 kg exerts 6.5 % more impact force

on the AFM when a damaged ice shield has a damaged foam than if it has new

foam.

The last mass is 1.549 kg. The difference between double and damaged foam is 6.1

% where the damaged foam is worse. However the difference between new foam

and double foam is 22.4 %. The mass of 1.549 kg exerts 22.4 % more impact force

on the AFM when a damaged ice shield has new foam than if it has double foam

and that is significant difference.

27

4.4.3 Repaired Ice Shield

Damaged Foam New and Double

Foam

New and Double Foam

Damaged Foam

Damaged Foam

New and Double Foam

New Foam

Double Foam

Damaged Foam

900

1100

1300

1500

1700

1900

2100

17 22 27 32 37 42 47

Impa

ct F

orce

[N]

Deformation [mm]

Repaired Ice Shield

0.339 kg

0.684 kg

1.380 kg

1.549 kg

Figure 16: Graph of Repaired Ice Shield were New, Damaged and Double Foam

are Compared

28

Table 7: Graph of Repaired Ice Shield were New, Damaged and Double Foam

are Compared


Repaired Ice Shield Impact velocity = 9.9 m/s

0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)


Damaged Foam 17.5 953 25 1346 32 2122 43 1772

New Foam 18 927 24.5 1373 34.5 1968 39 1954

Double Foam 18 927 24.5 1373 34.5 1968 42.5 1793

For the graph on Figure 16 we do the same comparison as in the previous chapters

but now with repaired ice shield. We begin with 0.339 kg. The difference between

new and double foam is nothing. Between damaged foam and, new and double

foam the difference is ∆AIF = (953N−927N)927N

· 100 = 2.8 % where the damaged foam

is worse.

The next mass is 0.684 kg. The difference between new and double foam is also

nothing. Between damaged foam and, new and double foam the difference is 2.0

% where the new and double foams are worse.

The next mass is 1.380 kg. The difference between new and double foam is yet

again nothing. However the difference between damaged foam and, new and dou-

ble foam is 7.8 %. The mass of 1.380 kg exerts 7.8 % more impact force on the

AFM when a repaired ice shield has a damaged foam than if it has new or double

foam.

The last mass is 1.549 kg. The difference between double and damaged foam is

1.2 % where the double foam is worse. However the difference between new foam

and damaged foam is 10.3 %. The mass of 1.549 kg exerts 10.3 % more impact

force on the AFM when a repaired ice shield has new foam than if it has damaged

foam.

29

4.5 Impact Force Compared to Kinetic Energy

900

1100

1300

1500

1700

1900

2100

2300

15 25 35 45 55 65

Impa

ct F

orce

[N]

Kinetic Energy [Joules]

Impact Force vs Kinetic Energy

New

Repaired

Damaged

Figure 17: Graph Comparing Strength of New, Damaged and Repaired Ice Shield

On the graph in Figure 17 we compare impact force to the different kinetic energies

from the masses. As seen on the graph the damaged ice shield transfers always

more impact force to the AFM than new or repaired ice shield. We also see that

a repaired ice shield transfers always less impact force to the AFM than new or

damaged ice shield.

30

4.6 Three Point Flexure Test

Table 8: Three Point Flexural Test

Repared Repared Repared New New New Damaged Damaged Damaged

Def. (mm) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N)

0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

2 10 10 20 30 20 30 10 10 50

4 30 30 40 80 40 70 10 20 90

6 50 50 50 130 80 110 20 20 130

8 60 70 70 170 110 150 30 30 170

10 70 80 80 200 150 180 30 40 170

12 80 90 90 230 170 200 40 50 190

14 80 90 90 250 190 210 40 50 200

16 80 90 100 230 200 220 50 60 210

18 80 90 100 230 200 230 50 60 230

20 80 100 100 180 210 230 50 60 230

22 90 100 110 180 200 230 50 60 200

24 90 100 110 180 210 230 50 60 220

26 80 100 110 180 210 230 50 60 190

28 80 100 100 180 210 230 50 60 180

30 80 100 110 180 210 220 40 60 170

-50

0

50

100

150

200

250

0 5 10 15 20

Forc

e (

N)

Deformation (mm)

New

Damaged

Repaired

Damaged

Figure 18: Three Point Flexure Test Data

31

Figure 19 shows the force needed to drive the loading actuator through the ice

shield specimen. These results are very different from the results from the impact

force experiment. The ice shield is made of six layers of composites. Four of the

layers are aramid fibers, which are very flexible. The remaining two layers are

glass fibers. The fiber direction is the same for all six layers and that makes the

structure weak against bending forces. This gives the ice shield high flexibility

which is essential against impact forces.

The result for one of the damaged ice shield specimens was very different from the

other damaged ones. This specimen had intact paint which concluded that the

paint was also important in order to remain the original strength. It was difficult

to break the specimens, but the graph shows the material strength even though it

does not show the break.

5 Discussion

5.1 Strength Comparison of Ice Shields

5.1.1 Remaining Strength of Damaged Ice Shield

Here is a comparison of strength of a new and a damaged ice shield. As mention

in chapter 3.6 the results of the 1.549 kg test was unreliable. It will not be used

in this comparison. As seen on the graph in Figure 12 the result from the 0.684

kg was 0.86 %. That is within the fail margin. Both the other masses show that

a damaged ice shield transfers more impact force to the AFM than a new one. It

can be concluded that the strength of a damaged ice shield is less than of a new

one. How much less strength it has is difficult to measure using this method. It

requires more advanced testing method.

The results from these tests do not give an accurate value of the difference between

a new and a damaged ice shield in reality. The size of the damaged area on

the ice shield is smaller than the impact area of the dropped mass. For more

accurate results the ratio between the impact area and the damaged area should

be considered.

32

5.1.2 Remaining Strength of Repaired Ice Shield

Here is a comparison of strength of a new and a repaired ice shield. As mentioned

in chapter 3.6 the results of the 1.549 kg test was unreliable. It will not be used

in this comparison. As seen on the graph in Figure 13 the AIF difference between

new and repaired ice shield from the 0.684 kg was 1.24 % and the 1.380 kg mass

was 4.52 %, both are within the fail margin.

The result from the remaining mass of 0.339 kg shows that a repaired ice shield

transfers less impact force to the AFM than a new one. It can be concluded that

the strength of a repaired ice shield is equal to or more than the strength of a new

one. Even though the differences are very small and most of them are within the

fail margin. The repaired ice shield did always transfer less impact force to the

AFM than the new one.

5.2 Comparison of Foam

We did set measurement fail margin to 5 %. When the measurements were done

we noticed that the results we got with the 1.549 kg were different then with the

other three smaller masses. After some consideration, we concluded that we could

not trust 1.549 kg results. The material in the AFM had become weaker and the

plywood had probably started to delaminate. When we did the test with the last

mass of 2.370 kg the AFM broke. We also think that the ice shield was starting

to get weaker for the same reasons.

When we compare the graphs on Figure 14, 15, 16 the first thing we see is that

many results can be eliminated due to the 5 % fail margin. With the remaining

results of 0.684 kg on Figure 14, 0.339 kg and 1.380 kg on Figure 15 and 1.380

kg on Figure 16. We see clearly that almost all the time the damaged foam is

performing poorly. The difference between new foam layer and double new foam

layer is almost nothing. However even though a damaged foam layer performs

worse the new foam layer the difference is not that significant. 7.8 % was the most

difference with 1.380 kg on Figure 16 and such a small difference does not justify

any new maintenance procedure where the ice shield is removed just to replace the

foam layer.

33

However it is clear that when an ice shield needs to be repaired, it is essential that

the foam layer is replaced.

5.3 Economical Issues

When an ice shield is damaged and needs to be repaired a decision has to be made

whether to repair it or replace it with a new one. Our results show that a dam-

aged ice shield can regain its original strength back if it is repaired. However the

economical side should be considered. The prices of new ice shields with paint and

the cost of repair for an ice shield are listed below:

New ice shield with paint for the 100 series costs about 39 000 NOK

New ice shield with paint for the 300 series costs about 48 000 NOK

Repair price including paint for ice shield for all DHC-8 series is about 30 000 NOK

From the list above we see that the price difference between a new ice shield for the

100 series and the repair cost is only 9 000 NOK. For the 300 series the difference

is 18 000 NOK. However as explained in chapter 3.1 a repaired ice shield can weigh

up to 10 kg more than a new one. Each DHC-8 aircraft has one ice shield on each

side. If an aircraft has two repaired ice shields, it can weigh up to 20 kg more than

if it had two new ones. This difference will affect the operating cost of the aircraft

with respect to fuel consumption. How much it will affect the operating cost will

not be calculated in this report.

6 Conclusion

A repaired ice shield will have equal or more strength than a new one. The original

strength recovery of a damaged ice shield can be obtained by following the repair

procedures. A damaged ice shield will not give as good ice-impact protection as

a new or repaired one. However it was not possible to examine the remaining

strength related to the degree of damage.

34

6.1 Recommendation for Further Research

Although the experiment is done, there is still a certain amount of uncertainty.

Below is a list of recommendations.

• The measuring method is certainly very important to improve, in order to use

mass transfer closer to reality. The method that should be used to simulate

the ice impact ought to simulate the same mass transfer or momentum as in

the reality. One way that could work is to use air canon to accelerate the ice

to the propper velocity.

• It is also important to consider the size of the impact area because the effect

of the energy is less when the impact area is large. The paint must be

considered in the test because it changed the results as seen in Figure 19.

• The size of the ice shield should also be considered because as seen in Figure

9 it can be seen that the doubler implemented on the fuselage is outside of

protected area of the ice shield. A further study of the size of the impact

area should be done.

35

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flame retardant silicone spong.html

[14] Structural Repair Manual Xtension ENA Retrieved Mai 19, 2014, from

http://pmenard.ep.profweb.qc.ca/GENERIC%20SKIN%20REPAIR%20Q400

X.pdf

[15] Widerøe, (2006). Ata 30 Ice and Rain Protection.. B1 MAINTENANCE

TRAINING MANUAL Bod: Widerøe.

[16] Widerøe. (2014). Om selskapet Retrieved Mai 19, 2014, from

http://www.wideroe.no/om-wideroe/om-selskapet

[17] Wikipedia. (2013). Bombardier Dash 8 Retrieved Mai 19, 2014, from

http://en.wikipedia.org/wiki/Bombardier Dash 8

[18] Young, H. D., & Freedman, R. A., (2007). Sears and Zemansky’s university

physics: with modern physics (12th ed.). San Francisco: Pearson/Addison

Wesley.

37

http://www.silicone-sponge-supply.com/Silicone_Sponge_Silicone_Foam/Flame_Retardant_Silicone_Spong/flame_retardant_silicone_spong.html



http://pmenard.ep.profweb.qc.ca/GENERIC%20SKIN%20REPAIR%20Q400X.pdf

http://pmenard.ep.profweb.qc.ca/GENERIC%20SKIN%20REPAIR%20Q400X.pdf

http://www.wideroe.no/om-wideroe/om-selskapet

http://en.wikipedia.org/wiki/Bombardier_Dash_8

Appendices

A1 Aircraft Fuselage Mockup Drawing

A2 Certificate of Calibration

A3 Ice Shield Drawing

A4 Ice Shield Paint Procedure

A5 Inconclusive Tests

A6 Repair Drawing Crack Damaged

A7 Repair Drawing Generic Procedure

A8 Repair Drawing Permanent Repair Crack Damaged

A9 Repair Drawing Permanent Repair Puncture Damaged

A10 Weight Dropping Test Data

38

A1 Aircraft Fuselage Mockup Drawing

39

A2 Certificate of Calibration

43

A3 Ice Shield Drawing

50

A4 Ice Shield Paint Procedure

Ice Shield Painting Procedure.

Information from Axel Olsson painter at Drag Industrier in Bodø.

55

Ice Shield Painting Procedure

When the repair procedure is complete, the ice shield has to be painted. It takes

about 15 man-hours to complete the paint procedure on a repaired ice shield. It

has to be sanded, surface filler has to be applied to the surface, and then it is

sanded again before applying pinhole filler. The surface has to be sanded again,

then the pinhole primer is applied, it is then left to dry for 2-3 hours in a ventilated

room. Next it is sanded again and the excess pinhole primer is smoothed in order

to distribute the composite primer properly.

One hour of drying will be enough before the composite primer can be sanded.

Now the ice shield surface is ready to be painted. The surface is painted two times

with 20 minute intervals. The last step is to dry the paint in an oven for one hour

at 60o C. This paint job costs 17000–18000 NOK.

The procedure for painting a new ice shield takes about 4–5 man-hours. The first

step is to sand the surface, and then apply the primer, and then heating must be

applied to the surface before sanding the primer. The surface can now be painted

with 2 layers paint with 20 minute intervals. The surface only needs to be dried

in an oven for one hour at 60o C. This paint job costs 5000–5500 NOK.

56

A5 Inconclusive Tests

Inconclusive Tests

Dropping of 2.370 Kilogram Weight and Ice Blocks

57

2.370 Kilogram Weight

Table 1: 2.370 kg Mass

2.370 kilogram weight AIF (N) = Avg. impact force in newtons

Displacement in mm Impact velocity = 9.9 m/s

Damaged New Foam Double

Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)

New 61 116.6 1911

Damaged 66 116.6 1767

Repaired

We tried to test 2.370 kg mass to see if the ice shield and AFM would handle it.

We got two measurements before the AFM broke as seen in Table 1. With only

two numbers we couldn’t compare anything so this test was inconclusive.

Dropping of Ice Blocks

Table 2: 0.660 kg Ice

0.660 kilogram ice AIF (N) = Avg. impact force in newtons




New 33 32.5 984 32.5 32.5 999

Damaged

Repaired 15.5/57 32.5 2095/570

58






New 36.5 64.9 1779 33/24 64.9 1968/2706

Damaged

Repaired 32 64.9 2029






New 38 97.4 2563 32 97.4 3044

Damaged

Repaired 64 97.4 1522

To make the ice impact simulation as real as possible we were going to drop ice

blocks through the PVC pipe. But as described in chapter 3.6 we encountered

a problem when using ice blocks both because it was difficult to get a constant

mass all the time. Also some ice blocks had many cracks in them and others did

not. We got some measurements as seen in Tables 2, 3, 4 but the results were so

strange that we decided to abandon this method and the tests were inconclusive.

59

A6 Repair Drawing Crack Damaged

60

A7 Repair Drawing Generic Procedure

67

A8 Repair Drawing Permanent Repair Crack Dam-

aged

70

A9 Repair Drawing Permanent Repair Puncture

Damaged

78

A10 Weight Dropping Test Data

Weight Dropping Test Data

Results from weight dropping tests done at the mechatronic labora-torium at UIA

85

0.339 kg




Damaged KE (J) New Foam Double

Shield/Foam Foam (mm) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)

New 17 16.7 981 17 16.7 981 17 16.7 981

Damaged 15.5 16.7 1076 16.5 16.7 1011 17 16.7 981

Repaired 17.5 16.7 953 18 16.7 927 18 16.7 927

Damaged Foam1076 N

New Foam 1011 N

Double Foam 981 N

960

980

1000

1020

1040

1060

1080

1100

15 15.5 16 16.5 17 17.5

Damaged Ice Shield 0.339 kg Weight

Damaged Ice Shield

New Foam981 N

Double Foam981 N

Damaged Foam981 N

0

200

400

600

800

1000

1200

0 5 10 15 20

New Ice Shield 0.339 kg Weight

New Ice Shield

Damaged Foam953 N

Double Foam927 N

New Foam927 N

925

930

935

940

945

950

955

17.4 17.5 17.6 17.7 17.8 17.9 18 18.1

Repaired Ice Shield 0.339 kg Weight

Repaired Ice Shield

Damaged Ice Shield 981 N

New Ice Shield981 N

Repaired IceShield 927 N

920

930

940

950

960

970

980

990

16.8 17 17.2 17.4 17.6 17.8 18 18.2

Double Foam

Double Foam

Damaged IceShield 1011 N

New Ice Shield981 N

Repaired Ice Shield 927 N

920930940950960970980990

100010101020

16 16.5 17 17.5 18 18.5

New Foam

New Foam


New Ice Shield981 N


940

960

980

1000

1020

1040

1060

1080

1100

15 15.5 16 16.5 17 17.5 18

Damaged Foam

Damaged Foam

Figure 1: 0.339 kg Mass

86

On the graphs in Figure 1 we compare new, damaged and repaired ice shield with

0.339 kg mass that is dropped from a height of 5.02 m.

• Shield Comparison with Damaged Foam

Damaged ice shield transfers 1076 N impact force to the AFM. New ice shield

transfers 981 N impact force to the AFM. Repaired ice shield transfers 953

N impact force to the AFM.

Comparing new and repaired ice shield: ∆N = (981N−953N)953N

· 100 = 2.94 %.

This means that the new ice shield transfers 2.94 % more impact force to

the AFM than a repaired ice shield.

Comparing damaged and repaired ice shield: ∆N = (1076N−953N)953N

·100 = 12.91

%. This means that the damaged ice shield transfers 12.91 % more impact

force to the AFM than a repaired ice shield.

Comparing new and damaged ice shield: ∆N = (1076N−953N)953N

· 100 = 12.91



• Ice Shield Comparison with New Foam





· 100 = 5.83 %.




·100 = 9.06



87


· 100 = 12.91



• Ice Shield Comparison with Double Foam





· 100 = 5.83 %.




· 100 = 5.83




· 100 = 12.91



88

0.684 kg






New 22.5 32.7 1496 24.2 32.7 1390 24.2 32.7 1390

Damaged 24 32.7 1402 23 32.7 1463 23.5 32.7 1432

Repaired 25 32.7 1346 24.5 32.7 1373 24.5 32.7 1373

Damaged Foam1496 N

Double Foam1390 N

New Foam1390 N

1380

1400

1420

1440

1460

1480

1500

1520

22 22.5 23 23.5 24 24.5

New Ice Shield 0.684 kg Weight

New Ice Shield

Damaged Foam1402 N

New Foam1463 N

Double Foam1432 N

1390

1400

1410

1420

1430

1440

1450

1460

1470

22.8 23 23.2 23.4 23.6 23.8 24 24.2

Damaged Ice Shield

Damaged Ice Shield

Damaged Foam1346 N

Double Foam1373 N

New Foam1373 N

1340

1345

1350

1355

1360

1365

1370

1375

24.4 24.5 24.6 24.7 24.8 24.9 25 25.1

Repaired Ice Shield

Repaired Ice Shield

New Ice Shield1496 N



13201340136013801400142014401460148015001520

22 22.5 23 23.5 24 24.5 25 25.5

Damaged Foam

Damaged Foam



Repaired Ice Shield 1373 N

136013701380139014001410142014301440145014601470

22.5 23 23.5 24 24.5 25

New Foam

New Foam



Repaired Ice Shield 1373 N1370

1380

1390

1400

1410

1420

1430

1440

23.4 23.6 23.8 24 24.2 24.4 24.6

Double Foam

Double Foam


89



• Ice Shield Comparison with Damaged Foam





· 100 = 11.14

%. This means that the new ice shield transfers 11.14 % more impact force

to the AFM than a repaired ice shield.


·100 = 4.16




·100 = 6.70 %.

This means that the new ice shield transfers 6.7 % more impact force to the

AFM than a damaged ice shield.






· 100 = 1.24 %.




·100 = 6.56



90


·100 = 5.25 %.

This means that the damaged ice shield transfers 5.25 % more impact force

to the AFM than a new ice shield.






· 100 = 1.24 %.




·100 = 4.29




·100 = 3.02 %.



91

1.380 kg






New 31.5 67.9 2155 33 67.9 2057 33 67.9 2057

Damaged 31 67.9 2190 33 67.9 2057 31.5 67.9 2155

Repaired 32 67.9 2122 34.5 67.9 1968 34.5 67.9 1968

Damaged Foam2155 N

New Foam2057 N

Double Foam2057 N

2040

2060

2080

2100

2120

2140

2160

31 31.5 32 32.5 33 33.5

New Ice Shield

New Ice Shield

Damaged Foam2122 N

Double Foam1968 N

New Foam1968 N

1960198020002020204020602080210021202140

31.5 32 32.5 33 33.5 34 34.5 35

Repaired Ice Shield

Repaired Ice Shield




2110212021302140215021602170218021902200

30.8 31 31.2 31.4 31.6 31.8 32 32.2

Damaged Foam

Damaged Foam



Repaired IceShield 1968 N1960

19701980199020002010202020302040205020602070

32.5 33 33.5 34 34.5 35

New Foam

New Foam



Repaired IceShield 1968 N1950

2000

2050

2100

2150

2200

31 32 33 34 35

Double Foam

Double Foam

Damaged Foam2190 N

Double Foam2155 N

New Foam2057 N

2040

2060

2080

2100

2120

2140

2160

2180

2200

30.5 31 31.5 32 32.5 33 33.5

Damaged Ice Shield

Damaged Ice Shield

Figure 3: 1.380kg Mass

92








· 100 = 1.55 %.




·100 = 3.21




·100 = 1.62 %.








· 100 = 4.52 %.




·100 = 4.52



93

Comparing new and damaged ice shield: There is no difference between new

and damaged ice shield with new foam.






· 100 = 4.52 %.




·100 = 9.50




·100 = 4.76 %.



94

1.549 kg






New 40 76.2 1905 43.5 76.2 1752 45.5 76.2 1675

Damaged 49 76.2 1555 42.5 76.2 1793 52 76.2 1465

Repaired 43 76.2 1772 39 76.2 1954 42.5 76.2 1793

Damaged Foam1905 N

New Foam1752 N

Double Foam1675 N1650

1700

1750

1800

1850

1900

1950

38 40 42 44 46

New Ice Shield

New Ice Shield




1500155016001650170017501800185019001950

40 42 44 46 48 50

Damaged Foam

Damaged Foam




1700

1750

1800

1850

1900

1950

2000

38 39 40 41 42 43 44

New Foam

New Foam


New Ice Shield 1675 N


1400145015001550160016501700175018001850

40 42 44 46 48 50 52 54

Double Foam

Double Foam

New Foam1793 N

Damaged Foam1555 N

Double Foam1465 N

1400145015001550160016501700175018001850

40 45 50 55

Damaged Ice Shield

Damaged Ice Shield

New Foam1954 N

Double Foam1793 N Damaged Foam

1772 N1750

1800

1850

1900

1950

2000

38 39 40 41 42 43 44

Repaired Ice Shield

Repaired Ice Shield


95








· 100 = 11.14

%. This means that the new ice shield transfers 11.14 % more impact force

to the AFM than a repaired ice shield.


·100 = 4.16




·100 = 6.70 %.

This means that the new ice shield transfers 6.7 % more impact force to the

AFM than a damaged ice shield.






· 100 = 1.24 %.




·100 = 6.56



96


·100 = 5.25 %.








· 100 = 1.24 %.




·100 = 4.29




·100 = 3.02 %.



97