EVALUATION OF TRANSPORT AIRPLANE

MAIN DECK CARGO COMPARTMENT

FIRE PROTECTION CERTIFICATION PROCEDURES

Alvin Habbestad

Fred Duvall

Kevin Kuniyoshi

Weston Slifer

Roger Young

1 June 1988
EVALUATIONOf TRANSPORTAIRPLANEMAINDECK

CARGOCOMPARTMENTfIRE PROTECTIONCERTIfICATION PROCEDURES

1. EXECUTIVESUMMARY

a. Purpose

A team was formed to rev~ew the existing regulations,

policies and procedures >n place for the testing,

certification, operation and maintenance of main deck Class

B cargo or baggage compartments smoke and fire protection

for federal Aviation Regulations (fAR) 25 airplanes. This

investigation was initiated by the Manager, Aircraft

Certification Division, ANM-100, to determine the level of

safety established by existing criteria used in that

certification. In addition, the team was to develop and

present, as appropriate, recommendations for improved

fire/smoke protection for new and existing airplanes.

b. Problem:

A South African Airways Boeing Model 747-244B was lost over

the Indian Ocean November 28, 1987. While the cause of the

accident hasn't been determined, there was evidence of a

major fire on board the airplane, which developed from an

undetermined origin and progressed within the main deck

cargo compartment. 159 passengers and crew were lost as a

result of the accident. There was evidence of significant

heat present in the upper areas of the cargo compartment,

severe charring on top of the cargo, and charring and soot

in certain portions of the interior of the cargo

compartment. Smoke and soot had apparently penetrated past

the barrier separating the cargo compartment and passsenger

compartment and progressed through the main deck of the

airplane.

As a result, a review of the existing rules, policies and

procedures, was made to establ ish whether there were any

deficiencies which could have been contributing factors in

this accident, and whether any simi lar event was likely to

occur on other airplanes operated in the combination

passenger and cargo mode.

c. Investigation:

A team comprised of members from the Seattle Aircraft

certification Office, Long Beach Aircraft Certification

Office, and flight Standards Aircraft Evaluation Group lDet

with representatives from the Boeing Company, the McDonnell

Douglas company, Alaska Airlines, federal Express, and the

Los Angeles fire Department to discuss the lDanufacture,

testing, approval, maintenance, and training involved with

this kind of operation.

d. Conclusions:

The Team concluded the following:

1. The existing rules, policies and procedures being

applied to the certification of Class B cargo or

baggage compartments in terms of smoke and fire

protection are inadequate.
2. The use of pallets to carry cargo

compartments is no longer acceptable.

in Class B

3. While entry into the cargo compartment is available,

not all cargo is accessible.

4. It is unlikely that personnel

available to extinguish a

deep-seated fire).

would

fire

have the means

(particularly a

4a. The reliance on crew members to fight a cargo fire must

be discontinued.

4b. The quantity of fire extinguishing agent and the number

of portable extinguishers are inadequate.

4c. The level of visibility available

cargo compartment is not adequate

fighting a fire with a portable fire

in a smoke filled

for locating and

extinguisher.

5. Most existing transport airplane smoke or fire

detection systems were certified prior to FAR 25

Amendment 25-54 and are incapable of giving timely

lJarning.

6. There were differences in the smoke testing procedures

and criteria used from manufacturer to manufacturer,

prior to issuance of FAA Advisory circular (AC) 25-9.

e. Recommendations:

Because of the unsa fe design features described above. no

new designs should be approved to existing Class B criteria.

For previously approved designs, rulemaking should be

initiated to correct this unsafe condition as follows

1. The main deck cargo compartment

of safety equal to that of Class

or;

must provide a level

C cargo compartments

2. Existing main deck Class B cargo compartments shall

carry only containers meeting the following criteria.

All containers in Class B compartments used to carry

cargo must meet cargo liner requirements listed in FAR

25.855(a) (1) amendment 25-60, must contain a fire/smoke

detector and must have a fire extinguisher connected to

it. The extinguisher may be either an integral part of

the airplane or a portable system. It must be of a

type and of sufficient size and quantity to suppress

and control any fire within the container. Metal or

fiberglass containers meeting the intent of Class C

compartments with respect to smoke/fire detection and

extinguishing are acceptable.
l.

). Smaller Class B compartments meeting the original

intent of the rule, namely those that provide

accessibility to all pieces of cargo so that a person

can move each piece an~ reach any given item, may

continue to be approved 1n the Class B configuration.

Such an area would be similar in size to a Class A

compartment, or a large closet, and should be no larger

than 200ft), unless it can be shown that the geometry

of the larger volume would allow easy access to the

contents. Baggage areas in "VIP" airplanes, and cargo

compartments in smaller transport category airplanes

would be examples of such areas.

4. For either the Class B or Class C cargo compartments,

the following apply:

a. The response time of any requi~ed smoke/fire

detection system should be 1 m1nute or less

(ref: FAR 25.858, Amendment 25-54).

b. The smoke barrier between the cargo area and

the occupied area should be shown to exclude

smoke under the conditions described in AC25-9.

c. Hazardous material must be handled per the

applicable provisions of Part 178 of Title 49,

Transportation.
2.

Section

1.

2.

3.

4.

5.

TABLE Of CONTEN~~

Name

Executive Summary

a. Purpose

b. Problem

c. Investigation

d. Conclusions

e. Recommendations

Table of Contents

Introduction

a. Purpose

b. Scope

c. Background

synopsis of Meetings

facts, Analysis and Discussion

Page

1

1

1

1

1

2

4

5

6

13

a. Applicable federal Aviation 13

Regulations for Cargo Compartments

b. Regulatory History 16

c. Combi Air flow Control 18

d. Combi Compartment Sizes 19

e. Smoke Detection System 20

f. Cargo/Passenger fire/Smoke

Barriers 21

g. Fire Extinguishers 22

h. Fire Containment of Cargo

Containers 22

i. Cargo Compartment Liners 23

j. Probl~ms likely to Prevent Con- 23

verting from Class B to Class C

k. Crew Training 24

Appendix I - List of Participants 26
3.

a. Purpose:

INTRODUCTION

The team •••as established to determine the adequacy of existing

criteria establ ished for the certification, ere'" training, and

continued ai~orthiness of smoke and fire detection systems used

in transport airplane main deck Class 8 cargo compartments in

Combi airplanes.

The team's intent •••as to

updating the criteria

compartments.

b. ~'-

develop recommendations as necessary for

for certification of Class 8 cargo

The team •••as to address existing and future Class B cargo

compartments.

The follo•••ing subjects "'ereencompassed by the investigation.

a. Rules

b. Policies

c. Smoke/Fire Detection Systems

d. certification Test Procedures

e. Airline Cre'"Procedures

f. Cre•••Training

g. Airplane Design

h. The Operating Environment

c. Background:

A 80eing Model 747-2248 airplane •••as lost November 28, 1987, over

the Indian Ocean. There •••as evidence a major fire in the Class B

cargo compartment •••as a contributing factor to the crash.

Class B cargo compartments have been in use for approximately 40

years. Over that period of time, the size of the cargo

compartments has been enlarged many times over; however, the

criteria has changed relatively little for certification of the

smoke/fire protection systems. The consequence is having rufes

established for what "'as essentially hand loaded cargo being

applied to large pallets and containers that can be up to 10 feet

wide, 10 feet high, and 20 feet long.

The accident of the model 747-2248 has called for a

re-examination of the actual operating environment that exists

for the airplanes, and what action may be necessary for updating

the smoke/fire protection criteria. A series of meetings were

held to examine the issue, the synopsis of which follows.

/
4. SYNOPSIS Of MEETINGS

January 18, 1988 - A special review team was formed to

existing certification criteria for main deck Class

compartments on cambi airplanes, and to make

recommendations for changes and improvements that

necessary.

study the

B cargo

whatever

may be

January 27. 1988 - A meeting conducted by the Division Manager of

the Aircraft Certification Division, ANM-IOO, Mr. Leroy Keith,

provided some specific guidelines and concerns to the team.

Additional team member inputs were encouraged. The goal of April

30 was established for a completed report.

February 4. 1988 - A team meeting was held to discuss possible

topics to be investigated. The following areas were included:

a.

b.

c.

d.

e.

f.

g.

h.

i.

j .

k.

1-

m.

n.

o.

p.

q.

r.

s.

to

u.

v.

w.

x.

y.

Maintenance aspects of compartments and smoke/fire

activities.

Crew capabilities, responsibilities

2-Crew airplane considerations

Testing for fire vs. smoke

Crew training of fire/smoke fighting - Part 121

Amounts of extinguishing agent

Operational procedures

Combi airplane configurations

Access to fire fighting equipment

Existing rules, policies - FAR 25

Airplane ceiling and sidewall liners

Test results available from the FAA Technical Center

Known domestic users of combi airplanes

Known population"of combi airplanes world-wide

Capability and requirements for switching configurations for

a combi airplane

Requirements for sealing pallets

Requirements for structural containers/nets/curtains

Carrying of hazardous material

Operator requirements for training

Ability to get to fire area with fully loaded airplane

ongoing testing at Tech Center

Recurrent training requirements

Flight manual requirements

New fire detectors

Flammability of barriers
January 29. 1988 Presentation by Boeing to FAA Boeing

presented a proposed customer option which would provide

automatic fire knockdown capability by flooding the Class B cargo

compartment with Halon. This would establish a concentration of

approximately 6% Halon in less than 1 minute. This percentage of

Halon is effective to keep a fire from rekindling until it is

depleted to a concentration of approximately J\.

The Boeing Company had not completed its investigation and was

not prepared to provide information on the time duration the

minimum J\ accepted concentrations of Halon could be maintained.

February 11 - 12. 1988 - Meeting with the Boeing Company and FAA

on current configurations of Model 747 combis and what criteria

were used in certifying the airplane.

subjects addressed were

Airflow management

Operational procedure YRQD smoke detection

Smoke sensor equipment (vacuum/sampling tubes)

Reduction of air conditioning draw-through capabilities

Smoke evacuation procedures/1981 update

Use of fire extinguisher hose extension and nozzle to reach

a fire

Operational procedure of opening doors to relieve smoke in

airplane

Use of Underwriters Laboratories listings for hand held

extinguishers

Percent of light transmissivity vs. the ability of crew

member to cope with smoke and see source of fire

Hazards of using Halon due to breakdown into more hazardous

compound at high fire temperatures

Cargo barrier design to 9g's and barrier maintenance

The use of ionization smoke/fire dptectors on Model 747-400

(a customer option)

The various types of containers available and which would be

the most fire resistant.

Containers that would contain a fire

Protective covers to limit the growth of the fire

A visit to the 747 cargo mock-up was made. Protective breathing

equipment (full face mask and portable oxygen bottle) was donned.

Wearing that, and carrying the hand held fire extinguisher

(attached with an apptoximately 6 foot section of hose to the 8

foot wand) an attempt was made to proceed to the rear of the

cargo compartment which contained 6 maximum volume pallet loads.

It was evident the ability of a crew member to access and fight a

fire in the rear of the cargo compartment was restricted.

Accomplishing this task in a dimly lit, smoke filled environment

was considered to be nearly impossible.

It was brought out that the fire extinguishing agent had to be

deposited at the base of the fire to be effective, and the total

amount of agent could be spent in approximately 12 seconds.
February 16, 1988 Meeting wlth Alaska Airlines flight line

personnel. Reviewed the combi airplane configuration used on

Boeing Model 737 airplanes, This configuration had the cargo

forward of the passengers, just aft of the forward crew entry,

and on a regular basis the number of pallets/passenger seats was

changed several times a day, The seats were on pallets which

made them easily installed and removed. The cabin attendants for

the most part, reportedly remained in the aft portion with the

passengers. The fire extinguisher and wand were positioned

against a cargo net forward of the cargo. Alaska Airlines had

acquired a new device which, as part of the fire extinguisher

equipment, could penetrate the side of a rigid container. They,

however, did not have one to show us.

The condition of the cargo/passenger barrier was observed to have

some wear, as expected for this much use. If there was smoke in

the cabin, differential pressure was to keep the passenger area

free of smoke.

February 29. 1988 - Meeting with Alaska Airlines crew training

personnel. Discussions were held with the supervisor of flight

attendant training, safety, and pilot emergency procedure

training. They reviewed initial training and recurrent training

for Boeing Models 727,737 and McDonnell Douglas Model MD-80.

During initial training, crewmembers actually put out an oil pan

fire.

In initial training the crewmembers do not don all the equipment

(face mask) nor use a large fire extinguisher.

For initial and recurrent training for smoke in the airplane,

flight crews go through procedures in an actual cockpit, and

flight attendants have a mock-up where reduced visibility by use

of goggles is used in evacuation training,

For recurrent training, th~y discuss the procedurp-s, don the

mask, connect the wand, and put on asbestos gloves. They don't

conduct a walk around with the equipment in place.

During this meeting, we were shown the new container penetration

device referred to in the previous meeting. A demonstra::ion of

its use had not been observed. The device allows the curved

portion of nozzle to be removed, exposing a hardened tip to

puncture some types of containers and through which extinguishing

agent could be discharged.

The training of the cabin crew together with the flight crew is

very limited but steps were being taken to increase that.

In the event of a fire, the airline's emphasis is on landing the

airplane at the nearest airport. They take their basic operating

procedures from the Boeing and McDonnell Douglas operations

manuals and add their own company procedures for the final

version.

When the Boeing Company and McDonnell Douglas present revisions

to the operations manuals, Alaska often adopts those changes for

their own use.

On the Model 737 airplanes with a 2 man crew the copilot is the

fire fighter.
March 15 16, 1988 Meeting FAA Seattle, Boeing, National

Transportation Safety Board (NTSB), FAA, Washington D.C., South

African Directorate of Civil Aviation (DCA),

The representatives from South African Airways and the South

African DCA presented the scenario of the loss of the model 747

on November 28, 1987, as best they understood it. A range of

sUbj ects were then discussed, trying to establ ish the relevance

of each in terms of potentially contributing to the accident.

The subjects of fire/smoke detection, fire fighting procedures

and the means for crew to fight a fire were explored. Also, th~

specifications for types of cargo compartments were discussed.

A portion of time was spent discussing the deep-seated fire (as

opposed to the surface fire which can be more easily reached).

It was noted the pallets on the aforementioned flight were

covered with polyethylene which could trap the smoke, cause

additional heat build-up and prevent early detection of a fire.

It was surmised that given sufficient thermal expansion due to a

raging fire in the airplane cargo compartment, none of the

existing protective measures to prevent smoke penetration into

the passenger cabin would be of value, including cabin

differential pressure or other means.

The question of having a fire when beyond 180 minutes from a

suitable landing site was also discussed.

The amount of fire extinguishing agent available was discussed,

as well as training requirements for using the extinguisher. It

was noted there was approximately 12 seconds of useful Halon

agent in the 16 pound fire extinguisher bottle.

Test procedures - kinds of test smoke, and the use of actual fire

testing were discussed. No testing using an actual fire is

conducted on an airplane for certification purposes. It was also

brought out that no fire fighting expert was present during

testing or during proposed testing of the airplane/smoke

detection or fire protection systems.

The maintenance requirements and procedures

detector systems were described.

for fireismoke

A question was asked concerning

going on the pallet during normal

for inspections prior to loading.

to date.

visual inspection of material

operation, and the requirements

There is no known requirement

No specific cause for the loss of the airplane was proposed or

provided at the meeting. The recovery of additional debris and

data from the wreckage is still being carried out by the South

African government and South African Airways.

The DCA did request the FAA to review the existing certification

requirements to analyze whether adequate criteria are established

for the certification of Class B combi cargo compartments.
'''hemeeting closed with statements that the NTSB would support.

ehe DCA investigation with technical asssistance along with the

fAA pursuing recommendations covering certification of Class B

combi airplanes.

0arch 24. 1988 - Team visit to Federal Express, which operates a

McDonnell Douglas DC-10 with a Class E cargo compartment. The

main purpose of the visit was to familiarize the team with the

general layout of the DC-10, the cabin airflow patterns

smoke/fire detector locations, and procedures for controlling

smoke/fire on the airplane. The procedures for loading the

pallets were discussed as well as the requirement for hazardous

~aterial being placed in special containers at the front of the

compartment forward of the main cargo door. This placed those

two or three containers at the forward positions, side by side,

with fire extinguiGhers containing 91b. of Halon 1211 connected

directly to them by means of quick disconnect hoses. The upkeep

~f the airplane was noted to be excellent.

Aarch 24. 1988 - Team visit to Los Angeles International Airport

Fire Department Discussions were held with two of their

captains on procedures for the fire department training for

fighting an airplane fire on the interior and exterior. It was

emphasized they had conducted and part~cipated in continual

training and all members at the station had over twenty years

experience.

The captains stated that they would not send a fire fighter into

a smoke-filled environment without hands-on training, and without

using a buddy system. They emphasized the requirements to be

totally familiar with any equipment being used. They also stated

that regardless of the individual's training, they never knew if

that individual would approach and fight a fire until after that

individual had actually been observed fighting the fire in a real

situation.

It was expressed by the captains that using a crewmember to fight

a fire on an airplane without specific initial training and

continual ongoing practice would probably be unsuccessful and

would provide only a false confidence that the task will be

accomplished.

The fire department captains displayed a device to penetrate the

skin of the airplane and inject fire extinguishing agent. That

particular system was a two man system and was too large to carry

on an airplane, but the concept was worth reviewing. The system

is basically a pneuma.tic drill (nitrogen driven) which, after

penetrating a side window, etc. can then discharge Halon through

it's tip.

The captains indicated that they had offered a class to discuss

with pilots and crewmembers, their role as fire fighters and how

they could be of more assistance to aircrews in case of an

emergency landing, or a groun4 evacuation. only one person

attended, an airline captain from a foreign operator.

March 25.1988 - McDonnell Douglas presentation to the team. The

company presented the following:

Fleet configurations for DC-8's, DC-9's, DC-10's and MD-ll,

including the MD-li combi.
Cargo loading, pallet positioning ~ithin the airplane.

Crewmember access to the cargo area.

Smoke barrier design and maintenance.

Liner materials and installation.

Smoke/fire detection and extinguishing equipment

description. for testing, they had tried several different

kinds of smoke generators before deciding a specific type

met their requirements. It ~as noted that there is no

specific measuring criteria for what is "adequate" smoke

generation.

Smoke penetration prevention philosophy.

Airflo~ patterns ~ithin the passenger and cargo compartments

~ere described (the outflow valve is approximately mid-body) .

crew procedures; requirements for training crewmembers was

basically left to the operators unless the operator had a

specific training contract. In general, the company

provides the equipment, but has no responsibility to provide

training to the airl ine. There was not much information

provided from the airline to McDonnell Douglas on the

airlines training. It was not clear how all technical data

was provided to the operators for training.

McDonnell Douglas at this time has no known combi airplanes

with Class B cargo compartments in service. Six MD-ll combi

airplanes with the Class C cargo compartment have been

ordered.

April 4, 1988 - Meeting with fAA Technical Center representative

Richard Hill. He provided a copy of a video on various cargo

compartment container testing. He also provided technical

reports on the following: fire characteristics in cargo

compartments; fire containment in Class D cargo compartments;

fire extinguishing methods for new passenger/cargo compartment

fires; and burn through resistance of aluminum ceiling panels in

simulated Class D cargo compartment.

He also made his facility available for further testing should

specific requests be. made.

We did contact the FAA Technical Center to obtain any available

information about the effects of a thermal (fire) source in the

cargo compartment on the airflow and the slight positive pressure

differential that normally is maintained in the passenger

compartment. The technical center asked for some basic

parameters to use in making a computation. We assumed the

following for those purposes:

a. Cargo compartment,of 10,000 cubic feet

b. Passenger Compartment of 19,000 cubic feet

c. Passenger Compartment venti lation rate of 0.25 Cubic Feet

per Minute (CFM) per cubic foot of volume

d. cargo compartment ventilation rate of 0.17CFM per cubic foot

of volume

e. An initial positive pressure differential of 0.1 inches of

water pressure present in passenger compartment.

using those parameters in a gross analysis, the following was

determined:

a. A fire producing a constant 10,000 British Thermal

(BTU's) per minute would eliminate the 0.1 inch of

positive pressure differential by thermal expansion.

Units

water
b. A fire producing a constant 50, 000 BTU's per minute would

provide sufFicient thermal expansion to overpower the 0.1

inch of water positive pressure differential and drive

air/smoke into the passenger compartment.

c. A fire producing a constant 100,000 BTU's per minute would

consume all the oxygen in the compartment and that brought

in by the ventilation.

It should be recognized that normally an uncontained fire will

grow exponentially unless some means are present to limit or

control it. Each of the above J cases would occur within a

matter of a few minutes or more. For reference, burning one

pound of aviation fuel produces approximately 21,000 BTU's.
4. FACTS, ANALYSIS, AND DISCUSSION

A. Federal Aviation Regulations (FAR) Applicable to Combi's

For Cargo Compartments

These specific requirements, as part of the type certification

basis, are as follows:

1. FAR 25.851, formerly civil Aviation Regulations (CAR)

4b.3BO(a) & (b) and CAR 4b.383(a), second sentence and

4b.383(b)(3), Fire extinguishers. An approved portable

extinguisher must be readily available for use in a Class B

cargo compartment. It must have a type and quantity of

extinguishing agent appropriate to the kinds of fires likely

to occur where used.

2. FAR 25.1439, formerly CAR 4b.380(c), Protective breathing

equipment (PBE). PBE required for airplanes containing Class

A, B, or C cargo compartments.

3 • FAR 25.853, formerly CAR 4b.381, Compartment

This specifies criteria that materials used to

cargo compartments must meet.

interiors.

construct

4. FAR 25.855, formerly CAR 4b.382 and 4b.384, Cargo and

baggage compartments, Requires the compartment to be free of

controls, wiring, equipment, or accessories whose failures

would effect safe operation unless those items can't be

damaged by cargo, or their failure will not create a fire

hazard. Cargo can't interfere with functioning of fire

protective features, and heat sources can't ignite cargo.

In addition flight testing is required to show compliance

with FAR 25.857.

5. FAR 25.857(b), formerly CAR 4b.383 (less second sentence of

(a) and (b)(3).

Cargo compartment classification; The "Comhi" airplane main

deck cargo compartment has been certified as Class B. This

regulation specifies that sufficient access exists in flight

to effectively reach any part of the compartment with the

contents of a hand fire extinguisher; that no hazardous

quantity of smoke, flames, or extinguishing agent will enter

an occupied compartment; and that a separate approved smoke

or fire detector system be provided to give warning at the

pilot or flight engineers station.

6. FAR 25.858, Cargo compartment fire detection systems. This

regulation became effective September 11, 1980, with the

adoption of Amendment 25-54. It requires a visual indication

to the flight crew within one minute of start of fire, be

capable of detecting a fire at a temperature significantly

below that which decreases structural integrity, be

functionally checked in flight, and be effective in all

operating configurations and conditions.
7. FAR 25.1301, formerly

installation. Requires

and design appropriate

properly.

CAR 4b.600 and 4b.60l, Function &

that installed equipment be of a kind

to its intended function and function

8. FAR 25.1309, formerly CAR 4b.606, Equipment systems and

installations. As applies to the smoke detection system

requires the system to be designed and installed in a manner

to ensure it performs its intended function under any

forseeable operating condition. The system also required

design to prevent hazards to the airplane if it was to

malfunction or fail.
The following is a brief tabular summary of cargo

compartMent classification requirements as

applicable to the model 747:

CARGO COMPARTMENT CLASSIFICATION

fAR 25.857

REQUIREMENT

DETECTION MEANS

A

Crewmember

at sta.

B

Separate

smokej

fire

detector

C

Separate

smokej

fire

detector

D

None

E

Separate

smoke

fire

detector

Reg. Subparagraph

EXTINGUISHMENTj

SUPPRESSION

Reg. Subparagraph

(a) (1)

Portable

Implied

(a) (1)

(b) (J)

Portable

extinguisher

(b) (1)

(c) (1)

Builtin

extinguisher

(c) (2)

(e) (2)

Contain- None

ment

CONTROL OF

VENTILATION AND

DRAFT, TO OR

WITHIN

Reg. Subparagraph

MEANS TO EXCLUDE HAZARDOUS

QUANTITY OF

SMOKE, ETC.

FROM OCCUPIED

COMPARTMENTS

Reg. Subparagraph

ACCESSIBILITY

Reg. Subparagraph

FIRE RESISTANT

LINER

Reg. Subparagraph

NONE

NONE

YES

(a) (2)

NONE

NONE

YES

(b) (2)

YES'

(b) (1)

YES

(b) (4)

YES

(c) (4)

YES

(c) (J)

NONE

YES

(c) (5)

YES

(d) (J)

YES

(d) (2)

NONE

YES

(d) (4)

YES

(e) (J)

YES

(e) (4)

NONE

YES

(e) (1)

'CAR Amendment 4b-l0, effect).ve

requirement that while the aircraft

crew must be able to mOve by

compartment.

April 1959, deleted

is in flight, a member of

hand, all contents of

the

the

the
b. Regulatory History

Cargo compartments on civil transport aircraft go back a

considerable time. civil Air Regulation (CAR), Amendment 04-1

dated November 1, 1946, included the Class A, Class B, and Clas~

C cargo compartments in the regulation. These compartments had

the shared concept of (a) detection by a crew member while at

their duty station and (b) the suppression of the fire by the

crewmember when detected.

On July 20, 1950, Amendment 04-6 to CAR 04 added a Class 0 cargo

compartment classification to the transport category aircraft

certification requirements. As the need for an all-cargo

transport category. .aiq~lane dev~l?ped: the C~ass E cargo

compartment classlflcatlon certlflcatlon requlrements were

adopted with the issuance of CAR amendment 4b-lO, dated April 23,

1959.

It should be noted that with CAR Arndt 4b-lO the CAB specifically

deleted the requirements applicable to use Class B cargo

compartment "that while the aircraft is in flight a member of the

crew must be able to move by hand all contents of the

compartment". This deletion is considered to be consistent with

the requirements for class A and Class E compartments. The

preamble also discussed large volume cabins relative to

compliance with the conditions set forth for Class 0 compartments

because so much oxygen exists that prompt suppression of the fire

through oxygen depletion is not attainable, thereby indicating

the need to control the fire at a very early stage.

Parallel to the development of type certification requirements

for transport category aircraft cargo compartments was the

development of regulations restricting the carriage of hazardous

cargo on civil aircraft. This was very important as it was

becoming impractical to design an effective containment

capability for the many cargo possibilities that were developed,

and exist today. This supports the basic assumption of transport

category aircraft cargo compartment class certifications. that the

cargo must be packed,. identified, and be of materials as defined

in the applicable portions of Part 178, Code of Federal

Regulations, Title 49, Transportation.

Based on the above premise, the concepts of early detection,

protection of structure, a means of extinguishment or

suppression, and a means to preven~ the accumulation of hazardous

quantities of smoke, fumes, nOXlOUS gases, and flames in a

occupied compartment became the basis of the regulatory

requirements.

The FAA established the following policy/criteria as acceptable

means for showing compliance with the smoke detection and smoke

penetration requirements of CAR 4b.380 through 4b.384, which

became FAR 25.855 and 25.857:

1. Smoke detection must occur within 5 minutes of

initiation of smoke generation using only a small

quantity of smoke representative of an incipient fire

condition or a small fire that may only produce a small

quantity of smoke.

2. A very dense and large quantity of smoke must be

generated in the cargo compartment at the most critical

location for penetration, generally near the

cargo/passenger barrier.
3. This very dense smoke must be maintained within the

cargo compartment for a period of time sufficient to

establish that a stabilized air flow condition exists

and that the criteria of item 4 below is not exceeded.

4. A few small wisps of smoke (similar to that which comes

from a cigarette in an ash tray) may penetrate into an

adjacent occupied compartment, but there may not be any

significant build-up in any part of the compartment

prior to the appropriate emergency procedure being

completed. After the emergency procedure has been

completed, there cannot be any haze present in the

occupied compartment.

5. When using the access door to enter or exit the cargo

compartment, a sma11 amount of smoke may enter, but

must immediately dissipate.

It should be noted that the history of cargo fires, until more

recently, were shown to be baggage fires. Based on that type of

background, the early detection of a fire was believed to ensure

that significant amounts of heat were not generated. This

concept was considered to be consistent with the size of fire

represented by the Bunsen or Tirrill burner used for showing

compliance with FAR 25.853 and 25.855. This size burner has

recently been replaced, see Arndt. 25-60, for testing of some

cargo liners.

with the exception of the new regulatory requirement of FAR

25.858 which has not yet been applied to a new type design

transport, the current transport aircraft have been shown to meet

the above criteria.
c. Combi Air flow-Control

The air flow distribution design concept used for

airplanes generally introduces air into the passenger

compartments and main deck cargo area just below the

compartment ceiling levels. for dedicated Class B cargo

compartments, the air is often introduced from

distribution ducts located near the center line of the

ceiling or from duct drops along the sidewalls. For

airplanes that can be converted, the air is distributed

into the cargo compartment through the passenger system.

The air passes through the compartment and exits through

the floor level sidewall grilles. This air then moves

downward and through the cove area outside the lower lobe

cargo compartments, passing over the wing center section

in the process, to the outflow valve(s) located in the

fuselage pressure vessel. Outflow valves may be located

in the aft fusela'ge, mid fuselage, forward fuselage, or in

a combination of these locations. At the same time some

cabin air is drawn in to the overhead volume above the

passenger compartment ce il inq and/or into the f.loor beam

areas where part of the flow 1S collected by rec1rculation

fans and returned to the cabin air distribution system.

Example of an Air-Conditioning Duct System

AIR-CONDITIONJi-JG DUCT SYSTEM

(pASSENGER. CONVERTIBLE 8< COMBl AIRPLAN!::S)

JeNt'

f\lGHT

DlCK

I

67
d. Camhi Cornpartr.'\ept Sizes

Below is a table

cargo compartment

rate per minute

Airplane

listing approximate cargo

floor area, maximum and

Class B Cargo

Compartments

compartment volume,

minimum ventilation

Ratio*

Approx. Approx. Approx. Ventilation

Vol. Area Rate CFM/ft

(ft3) Floor MAX. MIN.

707-320C Min 1206 315 877 2.107

Max 4083 848 2631 4.237

727-100C Min 730 272 678 2.757

Max 1460 391 1100 2.588

737 Min 1571 234 418 0.608

Max 3580 549 1344 0.957

747 Combi 3 pack CFM\ 2 pack ' CFM)

6/7 9600 880 0.17 \ ft3 j 0.11 \

ft3O.67

Combi

12/13

DC8-

DC-61, -63, 1605 N/A N/A N/A NIl;

-71, -73

DC9/MD8O 257 285 NIl;

(cargo

\

*Ratio = Vent i r Pass. Vent

\ Cargo Vol. J \ Pass. Vol. ,

= ( CFM) ,{ C'FM\ 1ft''J I ft'J) \ ' Note the wide variance in Class B cargo compartment sizes and

ratios as defined above. A ratio greater than one indicates a

proportionately greater airflow per unit volume into the cargo

compartment while a ratio less than one indicates a greater

airflow per unit volume into the passenger compartment. The

ratio would not be the only factor but a value less than one

would imply a better ability to prevent penetration of smoke or

fumes into an occupied compartment assuming the same

configuration.
e. S~oke Detection System

Main deck cargo compartments of large transport airplanes will

generally be divided into smoke,detection zones, th~ number being

dependent on the compartment Slze. A smoke detectlon zone is a

given portion (volume) of the cargo compartment with a dedicated

smoke detector system that monitors the air in that area for the

presence of smoke. When smoke is detected in the zone, the

flight crew is alerted and the zone identified on the Flight

Engineer panel.

Smoke detector systems can be divided into two basic types. One

employs an air sampling tube with orifices in it and a line

connecting the sampling tube to the smoke detector and amplifier.

This type of detector system is powered by a vacuum sources such

as a bleed air operated ejector or a fan. The other type of

smoke detector system is essentially a free standing unit, i.e.,

one which is appropriately mounted within the compartment so that

as smoke reaches it, the smoke is drawn into the detection

chamber convectively. For both systems, when light transmission

in the detector is reduced by the presence of smoke to about 94

percent of that of clear air, a DC voltage signal is sent to the

amplifier. The amplifier on receiving this signal actuates a

relay providing a fire warning indication to the cockpit. This

indication must be visual and in some cases, is also an aural

alert.

The fire warning, both visual and aural, is given to the

pilot/co-pilot by the master fire warning indicators and the fire

warning module on the pilots' overhead panel. In addition, for

airplanes with a flight engineer station, the fire warning is

given by a warning light on the cargo smoke detection module.

This allows the flight engineer to determine in which zone smoke

detection has occurred. In all cases, the smoke detection module

includes a test switch to permit testing of each smoke detector.
45

f. Cargo/Passenger Fire/S::Ioke Barriers

Because of structural growth under pressurization loads and other

relative motions due to flight loads, it is difficult to design a

rnainta inable airtight seal. In add ition, for operational

convenience, the cargo/passenger barrier is designed to be

installed at several different body locations. The Combi

cargo/passenger barrier is not designed to be a skin to floor air

tight seal. The purpose of the barrier is to provide a

restriction that provides air flow directional control within the

airplane. This is to allow airflow only _ into the cargo

compartment from the occupied compartment but not from the cargo

into the passenger area. These features provide for a very small

positive pressure differential in the occupied compartment

relative to the cargo compartment.

In most transport airplanes, the cargo fire/smoke emergency

procedure calls for maximum ventilation and to shut off all

recirculation/supplemental fans. Therefore, the actual deterrent

to smoke penetration into the 'passenger area is that upon

detection of a cargo fire there 1S a means to assure that air

from the cargo compartment flows overboard rather than entering

the passenger and/or cockpit areas. This airflow control is

accomplished by providing a proportionately greater mass air flow

into the passenger areas than into the cargo area through

restriction valves in the ventilation distribution system, by the

passenger/cargo fire/smoke barrier, and by proper location of the

outflow valves for the speci fic cargo passenger conf iguration.

This is evidenced during certification flight testing of the

smoke detection equipment by the lack of smoke penetration into

the passenger compartment, even when the access door is opened

for individuals moving into and out of the cargo area during the

smoke penetration tests.
g. Fire Extinguishers for Combi Airplanes

The Boeing mixed passenger/cargo (Combi) airplanes, starting

with the Model 707, wez:e origin.ally,certifi",d with a 20 lb. dry

chemical hand-held f1re ext1ngu1sher w1th an Underwriter

Laboratories (UL) rating of JA-20B:C. This fire extinguisher is

used with an extension wand which allows the operator to reach

over or between the cargo pallets. In 1980, a 16 lb. Halon 1211

extinguisher UL rated at 2A-20B:C was approved as a replacement

for the dry chemical extinguisher when the manufacturer

discontinued production of the units for aircraft use.

FAA Advisory

recommends at least

of 2A-40B:C.

circular 20-42C, dated March 7, 1984,

lJ lbs. of Halon 1211 and a minimum UL rating

Boeing decided on a minimum UL rated fire extinguisher size

of 2A-12B:C based on a National Fire Protection Association

(NFPA) 10-1969 recommendation of a u;>it of "A" rating for 1250

square feet of floor area whe!e f1res of moderate size and

ordinary hazard may be expected 1n warehouse, mercantile storage

etc. The floor area of a six pallet Combi in the Model 747 combi

is approximately 880 square feet.

The McDonnell Douglas DC-8 had a 17 lb. dry chemical and

extension wand, however, Douglas stated there are none of their

airplanes currently configured as Combi's in commercial service.

The Air Force KC-l0 could be operated as a Combi. We understand

that airplane has a J4 lb. Halon 1211 fire extinguisher.

h. Fire Containment of Cargo Containers

The FAA Technical Center conducted a series of tests to

asseSS the fire containment capability of LD-J cargo containers.

These containers have a volume of approximately 150 cu. ft. Some

of the containers would not contain 'a fire but those constructed

of aluminum with aluminum doors or rigid fiberglass with a

fiberglass door contained the fire with no damage to the

container. An aluminum container with two six by eighteen inch

holes cut in the side also contained the test fire. A high

density polyethylene container with an aluminum door showed

minimal damage after the test.

Boeing has suggested covering the cargo pallets with a fire

resistant material. Discussions with Dick Hill of the FAA

Technical Center indicate that there are fire resistant materials

available although expensive. The primary concern is maintenance

of these coverings and to assure they are installed properly to

provide an air tight cover.
47

i. Cargo Compartment Liners

The Boeing Model 747 Combi and freighter and the McDonnell

Douglas DC-10 freighter use the insulation blankets as the cargo

liner on the ceiling and upper sidewall. The lower sidewall of

the Model 747 generally has passenger compartment sidewall panels

installed over the blankets and the DC-10 freighter has

fiberglass panels.

The narrow body models (707, 727, 737)

the passenger interior panels as the liner.

Passenger service Units (PSU's), etc. remain

it is converted to carry cargo.

Combi airplanes use

The overhead bins,

in the airplane when

Prior to FAR 25 Amendment 25-60, effective June 16, 1986,

all cargo compartment liner material was required to be tested in

accordance with the 45' test procedures currently described in

FAR 25 Appendix F, Part 1. These requirements were originally

listed in Para. 4b.383, later in Para. 25.857 and currently in

Para 25.855. This test exposes the liner material to a bunsen

burner flame for 30 seconds with the test specimen held at 45'

angle. To pass the test, the flame must not penetrate the sample.

FAR 25 Amendment 25-60 upgraded the test requirements for cargo

compartment liners in Class C and Class D cargo compartments.

These liners must be tested using a two-gallon-per-hour kerosene

burner. This burner produces a l700'F flame and the sample panel

is exposed for 5 minutes in either a horizontal of vertical

orientation depending on how it is to actually be installed in

the airplane. Again, the flame must not burn through the

material. In addition, the temperature on the upper side of the

test panel must not exceed 400 .F. Th is test procedure was

developed by the FAA Technical Center based on full-scale testing.

It is unlikely that the existing insulation blankets or the

passenger sidewall and ceiling panels would meet the new

two-gallon-per-hour kerosene burner test.

j. Problems likely to prevent converting an existing Class B to

Class C

Due to the large airflow through a typical passenger cabin,

adding a full-flood fire .extinguishin~ system to an existing

Class B cargo compartment 1S not pract1cal. The Halon will not

remain in sufficient concentration for more than a short period

of time. Boeing looked at the 12 pallet arrangement on the Model

747 and concluded that' 350 Ibs. of Halon 1301 would provide for

an initial concentration of 6 1/2\, but would decay to 3\ in 7

minutes and 1\ in 15 minutes •••ith a 2000 c.... ft. per minute

airflo.... A 3\ Halon concentration is generally accepted as the

minimum necessary to suppress a fire. Some reduction of airflow

is possible but a redesign of the system would probably be

necessary.

Converting to a Class C would also require relining the

interior. An NPRM has been issued to require materials that meet

either the ne... kerosene burner test or are constructed of

fiberglass to be retrofitted in Class C and Class D Compartments.
k. Crew Training

Crewmember emergency training is required for those persons being

used as creW'Illemberson air carrier aircraft. The specific type

of emergency training is listed in Federal Aviation Regulation

(FAR) 121.417, which must be provided to all creW'Illembers.

Air Carriers must submit a training program to the assigned

principal Operations Inspector (POI) for approval. Prior to

final approval of the program, the POI will conduct an on-site

review of the actual training classes and course content. Once

satisfied that the training program meets the minimum

requirements of the operating rule, the program will be approved.

No changes may be made to the program by the air carrier without

approval of the POI.

FAR 121.417(b)(2)(iii) states, in part, that emergency training

must provide the following:

(b)(2) Individual instruction in

function, and operation of emergency equipment.

the location,

(b)(2)(iii) Individual instructions on portable fire

extinguishers with emphasis on type of extinguishers to be used

on different classes of fires.

The above type training is included in the air carrier's training

program. In addition, FAR 121.417(3)(ii) states, in part, that

"instruction in handling of emergency situations including fire

in flight and smoke control procedures" must be provided.

The aircraft manufacturer develops procedures during the flight

testing phase for eliminating smoke in the aircraft. Those

procedures are included in the manufacturer's cockpit checklist.

The air carrier makes up their own checklist based on the

manufacturer's checkli~t, which must then be approved by the POI.

Crewmember training is conducted based on information contained

in the checklist.

Additional emergency drill requirements must be accomplished

during initial training and once each 24 calendar months during

recurrent training. Each crewmember must operate each type of

hand fire extinguisher installed in the aircraft.

Although the above training does not include an actual fire

fighting drill which requ.ir~sextinguishing a fire, the operating

rules have been amended to ~nclude this. Effective July 6, 1989,

no crewmember may serve in operation unless that crewmember has

performed a fire extinguishing drill which also includes using

protective breathing equipment (PBE). When all crewmembers have

been trained in accordance with the new operating rule (FAR

121.417(d)), they will be better prepared to cope with actual

fires aboard the aircraft.

The training of crewmembers is considered adequate to handle

small fires which are exposed and readily accessible within the

aircraft cabin. History has shown that fires in galleys, seats,

lavatories have been extinguished by trained crewmembers.
B compartments on wide body aircraft

different environment regarding fire

Large separated Class

created a completely

fighting.

The compartment could be filled with large containers, or pallets

which would make accessibility very difficult in trying to locate

the fire. If the compartment filled with smoke, the situation

would be extremely difficult.
Appendix I

List of Participants

Federal Aviation Administration

F. Duvall ANM-270S

A. Habbestad ANM-lJOS

K. Kuniyoshi ANM-lJOL

W. Sl Her ANM-lJOS

R. Young ANM-l20S

W. Ashworth ANM-lOOS

B. Donner Washington D.C.

R. Hill Tech Center

F. Jenkins ANM-lJOL

L. Keith ANM-lOO

G. Lium ANM-1l2

D. Klempel ANM-lOJS

K. Olson ANM-l20L

Team Member

Team Leader

Team Member

Team Member

Team Member

Seattle Aircraft Certification Office Manager

Aircraft Certification

Division Manager

National Transportation Safety Board

M. Birky

B. Richardson

B. Strauch

Los Angeles International Airport Fire Department

captain Shook

Captain Wigfield

Republic of South Africa

B. Jordaan - Department of Civil Aviation

R. Van zyl - Department of Civil Aviation

R. Davidson - South African Airways

Alaska Airlines

A. Peterson

S. Vincent

D. Wasserstrom

S. Wiggens

Federal Express

G. Layton

B. Malcki

- Engineering

- Training

- Training

- Training
The Boeing Company

J. Aydelotte

F. Bereswill

J. Boyle

E. Campbell

A. Abneter

J. Lee

C. McMillan

R. Metter

R. Miller

D. Moyle

B. Pigg

J. Simons

R. wilder

The McDonnell Douglas Company

A. Aggarwal

L. Anderson

G. Bartz

D. Deschaines

J. Drobnich

A. Erickson

J. Grieco

S. Hariram

W. Heath

P. Kiefer

J. Leland

T. Peacock

T. ottaviano

H. servais

B. Shook

E. Smith

W. Steelhammer

G. Stuffel

J. Tischler

L. Thompson

D. Williams