systems fire protection working group dta - grenoble, france june 21-22, 2003

Systems Fire Protection Working Group

DTA - Grenoble, France June 21-22, 2003

FAA Inerting System Flight Testing on an Airbus A320

William CavageAAR-440 Fire Safety Research

Federal Aviation Administration

AAR-440 Fire Safety R&D

Airbus Inerting Flight Test___________________________________

Outline• Goals and Objectives

• OBIGGs

• Instrumentation– System

– Center Wing Tank

– OBOAS

– Additional Parameters

• Analysis

• Data– System Performance

– Fuel Tank Inerting

• Summary



Testing Goals and Objectives• Validate the simplified inerting concept and

develop/expand upon existing system performance models

• Examine system sizing requirements

• Validate in flight inert gas distribution assumptions

• Examine potential operational effects on the ability of a system to maintain inert conditions in a fuel tank



OBIGGS - System Architecture• Uses Air Separation Modules based on HFM technology

– Excepts hot air from aircraft bleed system

– Cools, filters, and conditions air

– Air is separated by ASMs and NEA is plumbed to output valves to control flow

– OEA is dumped overboard, H/X cooling air deposited in cargo bay near outflow valve

– System configured to operate in high and low flow modes

• Prototype system controlled by control box in cabin that is connected to system with cable

• Install system in test aircraft cargo bay for simplicity sake



FAA OBIGGs Installation Drawing



FAA OBIGGS Installation



Instrumentation and Data Acquisition• Various thermocouples and pressure transducers used to

evaluate system performance

• OBIGGS system flow meter and 2-channel oxygen analyzer for NEA and OEA analysis

• Eight sample locations within the Center-Wing Tank (CWT)– FAA Onboard Oxygen Analysis System (OBOAS) utilized

• Aircraft parameters measured

• Airbus data acquisition system utilized– Full-up flight worthy DAS



System Instrumentation Diagram

Static Pressure Temperature

Spare [O2]


OEA [O2]

Temperature

Static Pressure

Temperature Temperature (FAA Reader)


NEA [O2]

Penetration Hole



Flow Meter



CWT Instrumentation

NEA DepositVent Location



OBOAS Mounted in A320 Test Aircraft



Test Plan• Operated system in two flow mode for a series of tests with a

39,000 ft cruise altitude and a high rate of descent (4k ft/min)– Descended to 3,000 feet for operational purposes

– Nine total tests, 6 relative to FAA testing goals and objectives

– Used OBIGGS in both a single ASM configuration and a 2-membrane configuration to evaluate sizing requirements

• Testing proved the FAA system concept, acquired system sizing data, and examined the effects of several operational conditions– Studied effect of fuel on an inert ullage

– Studied effect of the high flow mode on the inert ullage

– Studied effect of bleed air on the membrane performance



No.Airbus

Designator Date Description1 1969 8/18/04 Started with CTR TK not inerted (20% O2) and empty. 2 ASMs,

OBIGGS started 10 mins before take off. Low flow climb and cruise(39,000ft), high flow in descent (normal descent).

2 1970 8/19/04 Started with CTR TK inerted (9% O2) and empty. 2 ASMs, OBIGGSstarted 10 mins before take off. Low flow climb and cruise (39,000ft),high flow in descent (rapid descent).

3 1972 8/20/04 Started with CTR TK not inerted (20% O2) and empty. 1 ASM, OBIGGSstarted 10 mins before take off. Low flow climb and cruise (39,000ft),high flow in descent (rapid descent at beginning).

4 1973 8/21/04 Started with CTR TK not inerted (19% O2) and with 1.5t (23%) fuel allflight. 1 ASMs, OBIGGS started 10 mins before take off. Low flow climband cruise (39,000ft), high flow in descent (normal descent).

5 1974 8/22/04 Started with CTR TK not inerted (20% O2) and with 3t fuel normalusage. 1 ASM, OBIGGS started 10 mins before take off. Low flowclimb and cruise (39,000ft), high flow in descent (normal descent).

6 1976 8/27/04 Started with CTR TK inerted (10% O2) and with 3t fuel (46%) normalusage. 1 ASM, OBIGGS started 10 mins before takeoff. Low flow forentire flight (rapid descent).

Table of Airbus Flight Tests



Data Analysis• Calculation of bleed air consumed

)][21.0(

)][]([

2

22

Perm

PermNEANEABleed O

OOQQ

• Model of Ullage gas Oxygen Concentration

21.*)*()1()*()1()1()(22 TankTankOO VtUGOFVtUGOFmIGOFmtmtm

= Mass of oxygen in tank at time t = Mass flow rate of inerting gas (in terms of t)

IGOF = Fraction of oxygen in inerting gasΔρ = Change in Ullage Density due to Altitude ChangeVTank = Volume of Tank UllagemTank = Mass of Gas in Tankmair = Mass of air entering tank

)(2tmO

m

With: = NEA Oxygen Concentration = OEA Oxygen Concentration

NEAO ][ 2

PermO ][ 2

TankO mtmtUGOF /)1()1(2



Results - System Performance• System performed as expected with predictable ASM

dynamic charactaristics– Easily predicted with static measurements

• 2-membrane system configuration gave approximately double the NEA– Less at altitude probably due to OEA back pressure

• Bleed air consumption greater then expected– Aircraft bleed air pressures were higher then expected at altitude

• ASM degraded during the ground and flight testing (~ 100 hours) giving about a 14% reduction in productivity– Not much more then normal expected “break-in” of ASM



0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100 120

Time (min)

[O2

] (%

vo

l)

0

10

20

30

40

50

60

Alt

(kf

t)/P

res

sure

(p

si)/

Flo

w (

scfm

)

NEA Line O2 (%)

ASM Inlet Pressure (Psig)

NEA Flow (SCFM)

Alt (kft)

Single Membrane Test

Switch to HighFlow Mode

System Performance Data



0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40 45 50

Time (min)

Flo

w (

scfm

) / [

O2]

(%

vo

l)

0

10

20

30

40

50

60

Pre

ssu

re (

psi

g)

NEA Flow (SCFM) NEA Flow (SCFM)NEA Line O2 (%) NEA Line O2 (%)ASM Inlet Pressure (Psig) ASM Inlet Pressure (Psig)

2 Membranes1 Membrane

One vs. Two ASM Performance Data



Bleedair Consumption Data

0

10

20

30

40

50

60

0 20 40 60 80 100 120

Time (min)

Flo

w R

ate

(SC

FM

)

NEA Flow (SCFM)

Bleedair Flow (SCFM)

Permeate Flow (SCFM)

Single Membrane Data



Results - Tank Inerting• CWT inerting accomplished easily

– No stratification observed, ullage acted in a very homogenous manner

• Two ASM inerting gave very little benefit compared to a single ASM– Different system “tuning” could change that

• High flow mode effective at helping maintain a low resulting ullage oxygen concentration during descent

• Fuel load had very little effect on measured ullage oxygen concentrations for both static and consumed fuel loads

• Simple model effective at predicting resulting ullage oxygen concentration given a system performance and mission profile



CWT Inerting Oxygen Concentration Data

0

5

10

15

20

25

0 20 40 60 80 100 120

Time (min)

[O2]

(%

vo

l)

0

5

10

15

20

25

30

35

40

45

Alt

itu

de

(kft

)

O2 Sample 1 (%)O2 Sample 2 (%)O2 Sample 3 (%)O2 Sample 4 (%)O2 Sample 5 (%)O2 Sample 6 (%)O2 Sample 7 (%)O2 Sample 8 (%)Alt (kft)




One vs. Two ASM Tank Inerting Data

0

5

10

15

20

25

0 20 40 60 80 100 120

Time (min)

Oxy

gen

Co

nce

ntr

atio

n (

% v

ol)

One Membrane

Two Membrane

Average Tank [O2]



High Flow Mode Benefit Tank Inerting Data

0

5

10

15

20

25

60 65 70 75 80 85 90 95 100 105

Time (min)

Oxy

gen

Co

nce

ntr

atio

n (

% v

ol)

High Flow Descent

Low Flow Descent

Average Tank [O2]Single Membrane



Effects of Fuel Tank Inerting Data

0

5

10

15

20

25

0 20 40 60 80 100 120

Time (min)

Oxy

gen

Co

nce

ntr

atio

n (

% v

ol)

Empty Tank

Consumed Fuel Load

Average Tank [O2]Single Membrane



System Performance Data

0

5

10

15

20

25

0 20 40 60 80 100 120

Time (min)

Oxy

gen

Co

nce

ntr

atio

n (

% v

ol)

0

10

20

30

40

50

Alt

itu

de

(kft

)

Flight Test Data

Model Data

Altitude




• FAA simplified OBIGGS concept validated– System performance predictable

– Bleed air consumption significant

– ASM performance degradation needs to be studied further

• Fuel tank inerting– Inert gas distribution accomplished easily

– System tuning needs to be studied further to say true benefit of 2 ASMs versus 1

– Two flow mode beneficial

– Fuel load effected resulting ullage oxygen concentration very little

– Ullage inerting easily modeled given a system performance

Summary

systems fire protection working group dta - grenoble, france june 21-22, 2003

Documents

test planoperated system

cableinstall system

faa system concept

system sizing data

simplified inerting

low flow modesprototype

test aircraft cargo

faa testing goals