a technical of forfor agent

A A Technical Review Technical Review of Methodologies for of Methodologies for Calculating Firefighting Agent Quantities Calculating Firefighting Agent Quantities Needed to Combat Aircraft Crash FiresNeeded to Combat Aircraft Crash Fires

Hughes Associates, Inc.SRA , International

FAA, Hughes Technical Center

Summary

PurposePurpose• Large frame aircraft may pose new challenges

– Full length, multi‐deck passenger levels– Increased fuel loads– Widespread use of composite materials

• Is the current “critical area”

concept adequate for these new challenges?

THERE IS NO COMPELLING REASON TO SIGNIFICANTLY REVISE THE NFPA 403

QUANTITIES OR METHODOLOGY

ApproachApproach

• Review historical basis• Conduct airport accident

review

• Conduct hazard analysis• Assess methodology

Review Historical BasisReview Historical Basis

• Analysis– RFFP 1970‐1972– GBA 1971 – EASAMS 1972– ARAC 2004

• Regulatory– CFR Part 139– ICAO ANNEX 14– NFPA 403 ‐2009

• Guidance ‐

FAA AC 150/5210‐6D (NFPA 403)

TCA, PCA, & Concept of Q TCA, PCA, & Concept of Q ––

Agent Agent Needed to Protect OccupantsNeeded to Protect Occupants

Q1

– ControlQ2

– Continued fire control and/or completeextinguishment

Q3

– Combat interior aircraft fire (NFPA 403)QT

= Q1

+Q2

+Q3

QQ 11

• Q1

= PCA x R x T, where:– T = time of application

(1 min for control of the PCA)

• TVEH RESP

+ TControl

≤

TOCC EXP

• 2 min + 1 min = 3min

– R = foam application rate

(e.g., 0.13 gpm/ft2

for AFFF)

SummarySummary

ofof

CurrentCurrent

MethodologyMethodology• Technical Basis TCA/PCA Concept and “Q”

agent quantities

– Test data– Hazard analysis– Crash data

• AC Categories (Indexes) based on L X W• Q1

–

maintain fuselage integrity• Q2

– final extinguishment (not necessarily a rescue path)• Q3

– NFPA interior attack (NFPA 403 only)• FAA CFR – More than NFPA Q1

; less than Q1

+Q2– extinguish the aircraft footprint?

• FAA AR 150/5210‐6D = NFPA 403• ICAO – NFPA 403 Avg

Q1

+Q2

Airport Accident ReviewAirport Accident Review• ARFF Assisted Accidents are Infrequent but do Occur

– 73 ARFF Response to Actual Fire Incident (1230 reviewed

1992‐present)• 11 – non‐survivable• 33 ‐

occupants self evacuated (Unassisted)• 29 – ARFF assisted

– Passengers ambulatory –

most evacuate before ARFF arrival

– Fatal crashes – ARFF may assist in evacuating some occupants

HazardHazard

AspectsAspects

fromfrom

LossLoss

DataData

• Fuel Spill Size– Historical – 26 of 33 incidents

< 53% of L X W– No quantitative way to

predict the spill size and

growth –

assume unlimited

spill size potential in the

anaklysis• ARFF Response Times• ARFF Fire Control Times/Agent

Quantities• Interior firefighting ?

ReaffirmReaffirm

PerformancePerformance

ObjectivesObjectives

• Protect ambulatory occupants – prevent heat penetration to intact

aircraft

• Prevent thermal threat to evacuating passengers

• Have sufficient agent to:– Establish safe area for continuous rescue and recovery

efforts

– Affect final extinguishment of all exterior and interior fires

Fuel spill areaFuel spill area

Fuel spill areaFuel spill areaFuel spill area 2Fuel spill area 1 Fuel spill area 2Fuel spill area 1



Spill area at t1

Spill area at t2 Spill area at t3

Spill area at t4

Spill area at t5

Spill area at t1

Spill area at t2 Spill area at t3

Spill area at t4

Spill area at t5

Spill area at t1

Spill area at t2

Spill area at t3

Spill area at t4

Spill area at t5Spill area at t1

Spill area at t2

Spill area at t3

Spill area at t4

Spill area at t5

AB C

D

E

F G

LaLa La La

Initial spill offset distance, Si

Unlimited dimension

La La

Initial spill offset distance, Si

Unlimited dimension

Performance CriteriaPerformance Criteria• Intact fuselage !!!!• Performance criteria

– Prevent ignition of interior

• Melting of Al due to high

heat flux

• Skin/insulation heat

transfer ( data and

modeling)

– Prevent thermal threat to

occupants who have

exited the aircraft• Pain threshold ‐

2.5 kW/m2

Exposure Flux (kW/m2)

0 20 40 60 80 100 120 140 160

Pred

icte

d Ig

nitio

n Ti

me

(min

utes

)

0

1

2

3

4

5

6

7

8

Exposure Flux (Btu/s-ft2)

0 2 4 6 8 10 12 14

0.5 mm (0.02 in) thick skin1.0 mm (0.04 in) thick skin1.5 mm (0.06 in) thick skin2.0 mm (0.08 in) thick skin2.5 mm (0.10 in) thick skin

Low heat flux model

High heat flux model

Exposure Flux (kW/m2)

0 20 40 60 80 100 120 140 160

Pred

icte

d Ig

nitio

n Ti

me

(min

utes

)

0

1

2

3

4

5

6

7

8

Exposure Flux (Btu/s-ft2)

0 2 4 6 8 10 12 14

0.5 mm (0.02 in) thick skin1.0 mm (0.04 in) thick skin1.5 mm (0.06 in) thick skin2.0 mm (0.08 in) thick skin2.5 mm (0.10 in) thick skin

Low heat flux model

High heat flux model

AgentAgent

QuantityQuantity

• Volume 1 (Q1

)– Prevent interior aircraft ignition– Delivered over 60 seconds

• Volume 2 (Q2

)– Suppress fire to allow safe egress– Not time dependent

• The distance needed to be extinguished for a “favorable”

outcome

–

based on 0.13 gpm/1 ft2

burning area

La

La

Area suppressed betweent1 and t2 volume of agentapplied during time interval

OffsetSa(t) at t1 Offset

Sa(t) at t2

La

La

Area suppressed betweent1 and t2 volume of agentapplied during time interval

OffsetSa(t) at t1 Offset

Sa(t) at t2

ParametricParametric

EvaluationEvaluation• Aircraft Length

– Cat 9 ( 240 ft)– Cat 6 ( 159 ft)– Cat 4 (89 ft)

• Aircraft skin thickness– 0.02 and 0.1 in. thick

• Skin material– Aluminum and composite– Test 4 min burn through criteria

• Crash rescue arrival (response) time• Wind – 0–20mph

Initial Spill Offset (m)5 10 15 20

Tim

e to

Igni

te P

lane

Inte

rior (

min

)

0

2

4

6

8

10

12

14

16

Initial Spill Offset (ft)0 10 20 30 40 50 60

Time Region IV: fire department arrives afterinterior aircraft ignition

Time Region II: interior aircraft ignitionprevented by suppression fire beyond the 9.59 kW/m² (0.84 Btu/s-ft²) distance

Time Region III: Interior aircraft ignition unavoidable regardlessof suppression actions

Time Region V: interior aircraft ignitionnot predicted

Time Region I: interior aircraft ignitionprevented by suppressing fire to 9.59 kW/m²(0.84 Btu/s-ft²) distance

19.1

m (6

3 ft)

Incident heatflux is 9.59 kW/m²(0.84 Btu/s-ft²) at thisdistance

Initial Spill Offset (m)5 10 15 20

Tim

e to

Igni

te P

lane

Inte

rior (

min

)

0

2

4

6

8

10

12

14

16

Initial Spill Offset (ft)0 10 20 30 40 50 60

Time Region IV: fire department arrives afterinterior aircraft ignitionTime Region IV: fire department arrives afterinterior aircraft ignition









19.1

m (6

3 ft)

Incident heatflux is 9.59 kW/m²(0.84 Btu/s-ft²) at thisdistance

Initial Spill

Offset [ft]

Prevent Interior Ignition - Fire Department Arrival Time (min)

1.0 1.5 2.0 2.5 3.0 3.5 4.0

1.6 1,970 gal 5,000+ gal I.C.N.P I.C.N.P I.C.N.P I.C.N.P I.C.N.P




16.4 1,440 gal 2,400 gal I.C.N.P I.C.N.P I.C.N.P I.C.N.P I.C.N.P

19.7 1,340 gal 1,690 gal 5,000+ gal I.C.N.P I.C.N.P I.C.N.P I.C.N.P

26.2 1,140 gal 1,140 gal 3,500 gal 5,000+ gal I.C.N.P I.C.N.P I.C.N.P

33 930 gal 930 gal 1,130 gal 5,000+ gal I.C.N.P I.C.N.P I.C.N.P

39 730 gal 730 gal 730 gal 1,300 gal 5,000+ gal I.C.N.P I.C.N.P

46 520 gal 520 gal 520 gal 520 gal 1,100 gal 5,000+ gal I.C.N.P

52 310 gal 310 gal 310 gal 310 gal 310 gal 440 gal 5,000+ gal

59 110 110 110 110 110 110 110

63 none none none none none none none

Initial Spill

Offset [ft]

Assure Occupant Safety Outside AC - Fire Department Arrival Time (min)

1.0 1.5 2.0 2.5 3.0 3.5 4.0

1.6 6,980 gal 8,900 gal‡ 8,900 gal 8,900 gal 8,900 gal 8,900 gal 8,900 gal

3.3 6,980 gal ,850 gal‡ 8,850 gal 8,850 gal 8,850 gal 8,850 gal 8,850 gal



16.4 7,000 gal 6,040 gal 8,440 gal 8,440 gal 8,440 gal 8,440 gal 8,440 gal

19.7 7,000 gal 6,650 gal 8,340 gal‡ 8,340 gal 8,340 gal 8,340 gal 8,340 gal

26.2 7,000 gal 7,000 gal 4,630 gal 8,140 gal‡ 8,140 gal 8,140 gal 8,140 gal

33 7,000 gal 7,000 gal 6,810 gal 7,930 gal‡ 7,930 gal 7,930 gal 7,930 gal

39 7,000 gal 7,000 gal 7,000 gal 6,420 gal 7,730 gal‡ 7,730 gal 7,730 gal

46 7,000 gal 7,000 gal 7,000 gal 7,000 gal 6,420 gal 7,520 gal‡ 7,520 gal

52 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal 6,880 gal 7,320 gal‡

59 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal

63 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal 7,000 gal

66 6,910 gal

Fuselage

2 min. ARFF Response 3 min. ARFF ResponseSpill

Offset (m)

Q1 (gal)

Q2 (gal)

QT (gal)

Spill Offset

(m)

Q1 (gal)

Q2 (gal)

QT (gal)

0.02 in Al 12 730 7000 7730 16 310 7000 73100.10 in Al 5 1440 7000 8840 10 930 7000 7930

Wind Conditions

2 min. Response 3 min. ResponseSpill

Offset (m)

Q1 (gal)

Q2 (gal)

QT (gal)

Spill Offset

(m)

Q1 (gal)

Q2 (gal)

QT (gal)

0 12 730 7000 7730 16 310 7000 731020 mph, fuselage downwind 22.5 940 8350 9290 27.5 690 8350 9040

20 mph, fuselage upwind 1.5 130 3150 3280 2.5 30 3150 3180

EffectsEffects

ofof

FuselageFuselage

andand

WindWind

Initial Spill Offset (m [ft])

ARFF Arrival Time (min)

1.0 1.5 2.0 2.5 3.0 3.5 4.00.5 (1.6) 7,200 L (1,900 gal)1 (3.3) 7,000 L (1,850 gal)2 (6.6) 6,620 L (1,750 gal)3 (10) 6,230 L (1,650 gal)5 (16) 5,450 L (1,440 gal)6 (20) 5,070 L (1,340 gal)8 (26) 4,300 L (1,140 gal)10 (33) 3,520 L (930 gal)12 (39) 2,750 L (730 gal)14 (46) 1,980 L (520 gal)16 (52) 1,180 L (310 gal)18 (59) 430 L (110 gal)

19.1 (63) none

44

MinMin

BurnthroughBurnthrough

Criteria Criteria –– Prevent IgnitionPrevent Ignition

Initial Spill Offset (m [ft])

ARFF Arrival Time (min)

1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.5 – 19.1(1.6 – 63)

26592 L(7,000 gal)

20 (66) 26,110 L (6,910 gal)25(95) 24,180 L (6,400 gal)30 (98) 22,240 L (5,880 gal)35 (115) 20,310 L (5,370 gal)40 (131) 18,370 L (4,860 gal)45 (148) 16,440 L (4,350 gal)50 (164) 14,510 L (3,840 gal)60 (197) 10,640 L (2,810 gal)70 (230) 6,770 L (1,790 gal)80 (262) 2,900 L (770 gal)85 (279) 968 L (260 gal)

87.5 (287) none

4 Min 4 Min BurnthroughBurnthrough

CriteriaCriteria –

EgressEgress

to Safe Areato Safe Area

Response Region I, 2 min Arrival Time

CAT Est. Q1 +Q2

NFPA Q1 +Q2

NFPA - Est. NFPA QT

NFPA - Est. QT QT

FAA QT

FAA - Est. QT QT

9 7730 7070 -660 9570 1840 6000 -17306 3590 2500 -1090 3750 160 1500 -20904 1330 740 -590 1340 10 100 -1230

Response Region I, 3 min Arrival Time

CAT Est. Q1 +Q2

NFPA Q1 +Q2

NFPA - Est. NFPA QT

NFPA - Est. QT QT

FAA QT

FAA - Est. QT QT

9 7310 7070 -240 9570 2260 6000 -13106 3250 2500 -750 3750 500 1500 -17504 1250 740 -510 1340 90 100 -1150

Response Region II, 2 min Arrival Time

CAT Est. Q1 +Q2

NFPA Q1 +Q2

NFPA - Est. NFPA QT

NFPA - Est. QT QT

FAA QT

FAA - Est. QT QT

9 8130 7070 -1060 9570 1440 6000 -21306 3760 2500 -1260 3750 -10 1500 -22604 1400 740 -660 1340 -60 100 -1300

Response Region II, 3 min Arrival Time

CAT Est. Q1 +Q2

NFPA Q1 +Q2

NFPA - Est. NFPA QT

NFPA - Est. QT QT

FAA QT

FAA - Est. QT QT

9 7520 7070 -450 9570 2050 6000 -15206 3430 2500 -930 3750 320 1500 -19304 2160 740 -1420 1340 -820 100 -2060

CAT NFPA Q1

Est. Gal to Supp (L xW)

NFPA Q2

NFPA Q1+ Q2

FAA QT

9 2619 5957 4451 7070 6000

8 2095 4967 3185 5280 40007 1585 2864 2045 3630 30006 1245 1775 1245 2490 15005 863 1030 647 1510 CFR

4 468 807 247 740 CFR

Agent to Suppress Engulfed Aircraft Agent to Suppress Engulfed Aircraft (Gal of AFFF) (Gal of AFFF)

SummarySummary

ofof

HazardHazard

AnalysisAnalysis• If fire immediately ”immerses”

aircraft, ARFF may be

ineffective, – Even with quick (2 min) response– Benefit of new 4 min burn though criteria

• Q1

and Q2

conservatively estimated– Fuselage length is key parameter– Others factors are not predictive –

occupant and fuel

load • Other potential factors

– Composites– Debris field

• What about interior firefighting?

Composite Fire Hazard AssessmentComposite Fire Hazard Assessment

• Small scale –

0.56–0.91 gpm/ft2

• 4 gal/ft2@60 gpm

China Lake tests

• NFPA Class A material extinguishment– 16.4 MW/100 gpm– Efficiency –

25–50%

-or-

ARFF

Q1

ARFF

Q2

Extra Agent Required?

ARFF

Q1

ARFF

Q2

Q3 + mop upNo or minimal extra agent

Torch Ignition 1 minute after ignition 1.5 minutes after ignition

2.5 minutes after ignition 4 minutes after ignitionTorches Out

CFRP Exposed to Torch Burner with Insulation

Backing

15 seconds after torches

out

OngoingOngoingCompositeCompositeTestingTesting

What about InteriorWhat about Interior

Firefighting?Firefighting?

CAT Rep. AC

Est. Man. FFg Flow

(gpm)

Required NFPA 403 Q3

(gpm)5 BAE 146 43 1256 A320 81 1257 B727-200 88 1258 B787 258 2509 B747-200 416 250

45 = Q

Interior FirefightingInterior Firefighting• Indirect firefighting may be only

plausible quick attack– Personnel are unlikely to be able

to mount a quick, interior attack• Limitations of current boom piercing

technology• Agent for interior suppression should

be included in agent calcs• FAA interior materials fire properties

requirements• Conclusion on current Q3

– Cats 5–8 NFPA Q3

is sufficient– Large and multi deck AC (CATS 9–

10) may require additional agent

ExteriorExterior

FirefightingFirefighting

• Exterior Class A fire control

estimate

• Combustibility/contribution of

composites should be

determined

• Q3 quantities for large composite

aircraft ? Cat 10 for B787 until

answers are known?

• Does added debris contribute to

exterior firefighting

requirements?

• Impact of new 4 min burn though

criteria

ImplicationsImplications

ofof

aa

MajorMajor

CrashCrash

Summary of Agent Methodology AnalysisSummary of Agent Methodology Analysis

• NFPA Q1, Q2 and Q3 concepts – Confirmed and revalidated;

– Agent quantities appropriate • Q1 ‐

fuselage protection

• Q2 ‐

provide safe area ( plus secondary agents)

• Q3 – final exterior and interior– subject to validation of exterior firefighting requirements for

large composite AC ( CATS 9‐10)

• Categorization Based on Length is Appropriate

Methodology has been ValidatedMethodology has been Validated• Explicit goals and requirements should be

reestablished in NFPA 403– Assure

• Survivability of ambulatory occupants

• Ability of responders to perform interior fire attack, potential

rescue

of non‐ambulatory survivors, and recovery of victims

– Provide agent to :• Protect aircraft fuselage• Control fire exposing escaping occupants• Establish safe area for continued operations• Affect final extinguishment

• Prevent reignition

RecommendationsRecommendations• NFPA 403 potential modifications

– Clearly state performance goals in Annex B; add the new

FAA reports as updated information– Provide CAT 10 (500gpm/5000 gal ) NFPA Q3 for B787 until

there is test data ? Need for additional Q3 for CATs

9 & 10?

– Explicitly state that 2 deck aircraft (B747 & A380)are Cat 10– Provide an access vehicle and boom piercing nozzle where

multi‐deck aircraft operate• Consider boom technology for CAT 5 and above

– Provide handline

piercing nozzles for other CATS– Improve water resupply guidance/criteria

a technical of forfor agent

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