# 4 Attachment 1 to BA letter AW-CRJ/10/388 dated Jun 07, 2010



# COMPLIANCE PLAN ADDRESSING 14 CFR PART 25.981(a)(3)

The purpose of this compliance plan is to provide full details regarding BA’s approach to

demonstrating compliance with 14 CFR 25.981(a)(3). The complexity and level of effort

required in addressing this requirement has promulgated the need to develop a multidisciplinary certification plan that will provide more detail than what is stated in the

individual disciplinary certification plans submitted at the beginning of the CL-600-2E25

program.

Requirement: 14 CFR Part 25.981(a)(3)

Requirement text: “(a) No ignition source may be present at each point in the fuel

tank or the fuel tank system where a catastrophic failure could

occur due to ignition of fuel or vapors. This must be shown by:’

(3) Demonstrating that an ignition source could not result from

each single failure, from each single failure in combination with

each latent failure condition not shown to be extremely remote,

and from all combinations of failures not shown to be extremely

improbable. The effects of manufacturing variability, aging, wear,

corrosion, and likely damage must be considered.

BA Disciplines

Affected: Fuel Systems (primary), EMC, and Structures

Approach to Compliance

BA notes that the amended ignition prevention requirements in § 25.981(a)(3) require

consideration of factors such as aging, wear, and maintenance errors not previously

considered in past programs. This amendment (25-102) to § 25.981, which applies to

the fuel tank system, requires that the designs be protected from lightning strikes with

fault tolerant features.

BA has agreed with TCCA and FAA on an approach that will be used to demonstrate

compliance in a meeting held in Sept 2009. The approach must consider elements from

both systems and structures. BA’s approach is summarized as follows.

PHASE 1: Identification of Failure Modes

Structures :

An integrated Product Development Team (IPDT) was created with members from

Airworthiness, Design, Quality, Manufacturing and In-Service Engineering. The intent of

this team was to analyze the structural wing tank design and consider any possible

defect that could occur in the manufacturing process regardless of the probability of

occurrence. In addition, consideration was also made to in-service findings that were

reported to BA and the repeatability of these findings as well as any potential fatigue

findings gathered from two lifetimes of fatigue testing on a full-scale test article. A set of

# 5 

# failure modes was derived from this analysis. These results have been documented in

report RAZ-BA698-017 Rev --, “CL-600-2E25 Wing Tank Structural Survey in Support of

Compliance with AWM 525-14 CFR 25.981(a)(3)”.

PHASE 2: Classification of Failure Modes

Structures :

Each one of the agreed failure modes identified above in phase 1 were classified into

one of the following categories:

i) Not a potential ignition source

ii) Possible ignition source, fault tolerant

iii) Possible ignition source, not fault tolerant

It should be noted that this phase concentrates solely on classifying the failure modes

into one of the 3 categories above. In case ii), BA has reviewed the design and noted

that these failure modes are protected by two independent features that can potentially

be fault tolerant. In case iii), the failure cases are protected by one design feature.

Results of the classification of these failure modes are listed in RAZ-BA698-017 Rev A,

which was further amended at Rev B to incorporate comments received from TCCA.

PHASE 3: Substantiation via Test Data and Analysis

Structures :

The failure modes that are not ignition sources (category i) above) are eliminated in this

phase. The other two categories are analyzed further.

a) Fault tolerant items: BA has reviewed the list of these potentially fault tolerant items

and has developed a test scenario that will prove the validity of these items as being

fault tolerant. As part of phase 3, a test scenario will be submitted outlining the items

which require further testing along with a schedule to conduct these tests post

certification.

b) Not fault tolerant items: BA has reviewed the list of potentially non-fault tolerant items

and has concluded that substantiation shall be submitted in the form of a reliability &

safety assessment. It shall be proven that for these areas in question, it is unrealistic to

have fault tolerance since the summation of the fuel tank vapor ignition event

probabilities, will be shown to be extremely improbable.

Systems:

A review of currently existing data (from SFAR 88 and Special Condition SCA H2002-03

compliance) for system related components wa s performed. A fuel system memo was

written packaging all potential failure modes that were agreed at that time that can

potentially result into ignition sources. Features that eliminated potential ignition sources

were tested and the results captured in various substantiation reports. In demonstrating

# 6 

# compliance, BA would like to adhere to the following extract from the FAA policy memo

on the subject;

“A design architecture that can withstand single failures, but not multiple failures, that

could result in an ignition source, could potentially comply with § 25.981(a)(3) when

combined with either regular inspections at sufficiently short intervals, or when combined

with a monitoring device to verify the functionality of the protective features.”

BA, in addition to identification of the design changes that were introduced to correct

single failures resulting in ignition of system related components, will also identify

pertinent inspections in the Maintenance R equirements Manual (MRM) that can be used

to detect any anomalies in these protection features.

Finally, in areas where no protection features could be identified, Bombardier will

indicate which analysis and/or test reports were issued documenting an approach, which

justified that fuel tank vapor ignition was extremely improbable.

A schematic is shown on the next page, outlining the 3-phased approach to

demonstrating compliance with 14 CFR Part 25.981(a)(3).

# 7 

# "AWM25.981(a)(3)

Exemption - EMC Pr o 

# Systems Structure

N/A Identification of

potential failure modes

Classification of failure

modes

1) Ignition source

2) Fault tolerant

3) Not fault tolerant N/A

Provide test scenarios

for fault tolerant items

and probabilistic

analysis for non-fault

tolerant items Use previous data from

SFAR 88 / SCA H2002-03

to outline failure modes,

design changes,

inspections and probability

analysis 

# Phase 1

Phase 2

Phase 3 RAZ-BA698-017 Rev - -

RAZ-BA698-017 Rev B

RAZ-BA698-017 Rev C

Fuel system Memo



# Exemption request for

structural items (see

exemption request

form) 

# Compliance

This 3-phased approach will allow BA to petition for a partial exemption against structural

related items and to be granted the additional time necessary to complete the tasks required

to demonstrate compliance after CL-600-2E25 type certification (see attached EMC Project

Plan schedule). The exemption request will outline compensating factors that demonstrate

that the airplane is safe and that the extended time allowance to perform the additional

testing to achieve full compliance is acceptable and in the public interest.APR. 2 MAY 2 JUN. 2 JUL. 2 AUG. 2 SEP. 2 OCT. 2 NOV. 2 JAN. 2 FEB. 2 MAR. APR. 2 MAY 2 JUN. 2 JUL. 2 AUG. 2 SEP. 2 OCT. 2 NOV. 2 DEC. 2 JAN. 2 FEB. 2 MAR. APR. 2 MAY 2 JUN. 2 JUL. 2 AUG. 2 SEP. 2 OCT. 2 NOV. 2 DEC. 2APR. 2010 SEP. 20120. BA/TC/FAA TECHNICAL AGREEMENT 50% 26-Apr-10 28-May-100.1100% 26-Apr-10 7-May-100.20% 7-May-10 28-May-101. TEST CONFIGURATION & TEST PLAN 28-May-10 15-Nov-101.10% 28-May-10 28-Jul-101.20% 15-Aug-10 30-Aug-101.30% 6-Sep-10 10-Sep-101.40% 15-Sep-10 15-Dec-101.50% 15-Aug-10 30-Sep-101.60% 4-Oct-10 8-Oct-101.70% 11-Oct-10 15-Oct-101.80% 15-Oct-10 15-Nov-102.BAEX ACTIVITIES - TEST ARTICLES 15-Dec-10 5-Oct-112.10% 15-Dec-10 15-Sep-112.20% 15-Sep-11 30-Sep-112.30% 1-Oct-11 5-Oct-113.LIGHTNING TESTS15-Oct-11 30-Jan-123.10% 15-Oct-11 15-Jan-123.20% 15-Jan-12 30-Jan-124.ANALYZE/GATHER DATA15-Mar-12 15-May-124.10% 15-Mar-12 19-Mar-124.20% 19-Mar-12 15-May-125.REPORTS & APPROVAL15-May-12 15-Sep-125.10% 15-May-12 30-May-125.20% 15-May-12 15-Jul-125.30% 30-May-12 15-Sep-126.TC CommitmentAPR. 2010 SEP. 2012Task completedTask lateTC to review/approve BA submitted reports i.e. Test reports (submitted end ofMay 2012) & RAZ-BA698-017 (submitted mid-July 2012)LEGEND:BA EMC to submit test reports to TCBA EMC to prepare RAZ-BA698-017 report & submit to TCTest house to submit test reports to BABA EMC to review test reportsBA EMC & TC to witness tests at test houseTest house to ship test articles back to BABA Experimental to ship test articles to test houseBA & TC to hold final conformity inspection of test articles & hold test readinessreview meetingBA Experimental to build test articles (including BA/TC conformity inspections)BA EMC to finalise test plan & get TC's approvalBA EMC to hold internal peer review of draft test plan(s), test set-up(s) & passfail criteriaBA EMC to present draft test plan(s) to TCBA EMC to draft test plan(s), Test set-up(s) & pass fail criteriaBAEX CAD support for test article(s) drawing(s)BA EMC to present test configuration(s) for BA internal peer review (structures,EMC, A/W, BA experimental, etc.)BA EMC to present preliminary test article(s) configuration(s) to TCTechnical approach approved by TCBA EMC to create "paper " test articles with parts lists & test configurations 

# PHASE 3 PLAN for 25.981(a)(3) EXEMPTION - EMC PROJECT PLAN DEC. 2End Date% Complete Start DateBA EMC to present technical approach to TC25.981(a)(3) EXEMPTION - EMC MILESTONESBBCompleted25.981(a)(3) Exemption - EMC Project Plan.xls5/12/2010

# 8 

# Means/Method of Compliance

1) Fuel Systems

MOC = Design Review (DR), Data (D), Analysis (A)

Method of Compliance = A review of the design will show that the CL-600-2E25 design

changes do not impact the existing test data substantiation which will be used to

demonstrate compliance with this requirement. This data will show that certain areas of

the fuel tank design have been proven fault tolerant with a robust design, which

precludes any ignition sources in that area. In areas of the fuel tank that are not fault

tolerant, it will be shown that substantiating data exists, defining these areas as ones

wherein fuel tank vapor ignition is extr emely improbable. It will also be shown via

Analysis that regular inspections (where prac tical) exist as Airworthiness Limitations

(AWL) items in our Maintenance Requirements Manual (MRM) that can verify the

functionality of these protective features.

References:

- Fuel system design compliance report RAP-IN670-172;

- Fuel system memo CRJ1000/28/2010/001/EH dated 29 March 2010.

2) EMC

MOC = Design Review (DR), Data (D), Test (T), Analysis (A)

Method of Compliance = A review of the design will show that the CL-600-2E25 design

changes do not impact the existing test data substantiation which will be used to

demonstrate compliance with this requirement for “Systems” only. This data will show

that certain areas of the fuel tank design have been proven fault tolerant with a robust

design, which precludes any ignition sources in that area. In areas of the fuel tank that

are not fault tolerant, it will be shown that substantiating data exists, defining these areas

as ones wherein fuel tank vapor ignition is extremely improbable.

For structural design elements, test data will be provided for all elements of the structural

design where fault tolerance has been identified. Where fault tolerance has not been

identified, it will be shown via an analysis and/or test data that these areas are ones

wherein fuel tank vapor igni tion is extremely improbable.

References:

- EMC design compliance report RAE-BA670-176 “Aircraft Lightning Protection

Design Compliance Report, Direct Effects”;

- 

# EMC memo CRJ900-01-66-2010-26A dated May 12, 2010.

# 9 Attachment 2 to BA letter AW-CRJ/10/388 dated Jun 07, 2010



# EXEMPTION REQUEST APPLICATION FORM

Request made by : Bombardier Inc.

400 Cote-Vertu Road West

Dorval, Quebec, Canada

H4S 1Y9

Request made to: Federal Aviation Administration (FAA), New York

Aircraft Certification Office (NYACO) through the

offices of Transport Canada Civil Aviation (TCCA)

Date request made : 1) 23 Oct 2009 via letter AW-CRJ/09/694 (original

opening request)



# 2) 14 May 2010 via letter AW-CRJ/10/320.

14 CFR Provision(s) : 14 CFR Part 25.981(a)(3) “Fuel tank [ignition

prevention.]” at amendment 25-102

1- Requirement text :

14 CFR 25.981(a)(3) states:

“(a) No ignition source may be present at each point in the fuel tank or the fuel tank

system where a catastrophic failure could occur due to ignition of fuel or vapors. This

must be shown by:’

(3) Demonstrating that an ignition source could not result from each single failure, from

each single failure in combination with each latent failure condition not shown to be

extremely remote, and from all combinations of failures not shown to be extremely

improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely

damage must be considered.”

2- Reason for exemption request:

As explained in FAA policy memo ANM-112-08-002, before amendment 25-102, the

concept of lightning protection of the fuel tanks was normally applied in preventing

ignition of vapors in the tank area. There was no consideration of design failures, aging,

wear or maintenance induced errors to the fuel tank structure. As a result, the FAA

policy now specifies that compliance with 14 CFR Part 25.981(a)(3) would typically

require a design with three highly reliable, independent and redundant protective

features to prevent ignition in the event of a lightning strike. The structural elements of

the wing tank design of the Bombardier Aerospace (BA) CL-600-2E25 (CRJ1000) do not

comply with this requirement.

It was noted in the policy memo that the FAA determined that in certain cases it was in

the public interest to grant an exemption for structural related elements provided that

certain conditions are met ensuring an acceptable level of safety. In view of this

allowance, BA is applying for a two-part exemption for the structural elements of the fuel

# 10 

# tank design. Firstly, to demonstrate that the design complies with the requirement even

with only two independent, effective and reliable means of lightning strike protection.

Secondly, that the demonstration of compliance to this requirement be made after type

certification of the CRJ1000.

BA has implemented a compliance plan (Attachment 1) to meet the requirements of the

FAA policy in support of this exemption application, however, it has been concluded that

the analyses / assessments, compilation and documentation of the substantiating data

cannot be completed in time for CRJ1000 type certification on the basis that some of the

test data required to show compliance would not be available prior to this date. A

schedule has been included as part of this compliance plan outlining the milestones

towards the completion of this deliverable by the middle of September 2012.

System related design features associated with compliance to 14 CFR 25.981(a)(3) are

acknowledged to be not exempt from this requirement and shall demonstrate full

compliance as part of the CRJ1000 type certification activities.

3- Detailed Means of Compliance to the FAA Policy memo

For the fuel system elements and related components of the wing fuel tank design, full

compliance will be demonstrated and documented in the next update to the BA Fuel

Tank System Safety – Ignition Prevention Report, RBR-BA690-144, as part of the CL600-2E25 type certification activities. The details of this plan are outlined in the attached

BA Fuel System internal memorandum CRJ1000/28/2010/001/EH dated Mar 29, 2010

(Attachment 3).

For the structural elements of the CRJ1000 wing fuel tank design, in demonstration of

adherence to this policy in order to petition for an exemption, BA will show the following:

• For certain areas of the wing tank structure, the design includes at least two

independent, effective and reliable means of protection such that fault tolerance

is provided for each area of the design being sought for exemption.

• For areas of the design where it is deemed impractical or where fault tolerance

cannot be established, BA will present a risk analysis and/or test data where it

will be shown that fuel tank vapor ignition is extremely improbable.

The methodology that BA has used to achieve this goal is documented in report RAZBA698-017, “CL-600-2E25 Wing Tank Structural Survey in Support of Compliance with

AWM 525-14 CFR 25.981(a)(3)”. The report was submitted in phases and is currently

updated with data from phases 1 & 2 as described in the multi-disciplinary compliance

plan for § 25.981(a)(3) (Attachment 1). The results of the analysis to determine the

required test data, the availability of test data and/or additional testing required for the

fault tolerant and yet to be classified failure modes from phase 2, will be included in this

report once made available.

The following BA internal memoranda are attached herewith, providing the following

commitments:

• The EMC memo CRJ900-01-66-2010-26A dated May 12, 2010 (Attachment 4),

outlines the EMC plan to complete the established phase 3 activities where test

# 11 

# scenarios have been identified to show compliance for design features classified

as “fault tolerant”. BA commits to complete this exercise by September 2012, as

stated in this memo. Once all the test data are formally documented, BA will

update report RAZ-BA698-017 (at the next applicable revision), as prescribed in

the certification plan and formally submit to TCCA for review and acceptance.

• The RMAS memo (Attachment 5) outlines the procedures for a numerical

probability assessment of the non-fault tolerant items identified in phase 2.

Some of the work required for this phase is dependent upon data that will only be

made available in the commitment shown above in Attachment 4. The RMAS

memo also provides the commitment to perform and complete this exercise.

4- Compensating factors (Effect on safety):

To facilitate this partial exemption request, BA is offering the following as justification

that the design is safe even with only two means of protection for the structural elements

of the wing tank, as well as to justify allowing BA sufficient time after CL-600-2E25 type

certification to complete the tasks as noted in the above attachments. The following

section illustrates the design features that BA will be concentrating on, with supporting

data outlining the history of testing previously done.

4.1 – Protection features

4.1.1- Fasteners

The CRJ1000 wing box overall design concepts are identical to those of the

CRJ700/900. The upper and lower fuel tank skins are made from aluminum alloy planks

with integrally machined stringers spliced together. Fasteners at splices, rib/plank and

spar/plank interfaces are of the “Hi-Lite” type, which are installed interference fit. The

structural integrity of these design features for the CRJ700 and CRJ900 airplane models

are currently being proven during full scale fatigue testing. The test articles have so far

successfully accumulated 160,000 flights and more than 140,000 flights, respectively.

Bombardier Aerospace Process Specification (BAPS) 151-029 “Installation of Hi-Lite

Fasteners”, rigorously controls the installati on of the fasteners. BAPS 151-029 specifies

many acceptance criteria against which the fastener installation is checked. These

criteria include the specification of holes as well as installation. Some examples of these

criteria are hole diameter, hole/countersink angularity, pin protrusion limits, torquing,

flushness and visual inspection for cracked nuts. Any failure to meet the acceptance

criteria shall be cause for rejection.

In addition, all fasteners that penetrate the fuel tank are installed wet as per BAPS 157-

027, to preclude leakage and corrosion.

4.1.2 - Prior testing done on the early Challenger variants

As part of the original Challenger certification effort (CL-600-1A11), zone 2A direct

lightning strike tests were carried out on four fuel tank skin splice coupons. The coupons

were constructed using the same types of materials and processes as are used for

production aircraft. All coupons used representative fasteners that were installed using

the same pitch as on the aircraft. Both faying surface seals and fillet seals were used to

# 12 

# make the test articles production representative. The fasteners were wet installed;

however, there was no brush sealant over the fastener ends in order to facilitate hot spot

detection.

The tests included strikes to both the skin and the fastener heads. No sparking or hot

spots were detected. The test results are documented in BA report RAE-600-110, “CL600 Design Compliance Aircraft Lightning Protection”.

4.1.3 - Consideration of single point failure of the fastener

When considering the robustness of our fastener design / installation, BA assures

continuity of the fastener throughout the aircraft life and that there is no possibility of

installation / Q.A. perturbations which could result in a fastener mis-installation or failure.

Furthermore, the BA position is that there has been no in-service fastener cracking

reported, or any other scenario, which could l ead to arcing (since fastener continuity is

maintained as supported by fatigue testing). This is in consideration of the types of

fasteners used, the controlling specifications, Q.A. requirements, thickness of fastened

components, size and fastener material details, interference fit provided and historical

data, which demonstrates the effectiveness of our design.

4.1.4 - Sealant

Application of sealant to the fasteners is a common method of preventing fuel leaks and

is also used to aid in the prevention of an ignition source in the fuel tank during a

lightning strike. According to ‘Lightning Protection of Aircraft’ (Fisher, F.A., and Plumer,

J.A.), “the sealant acts to contain the arcs and sparks which occur at these fasteners

during a strike attachment and prevents contac t of the arc products with the fuel vapor

space.”

As previously mentioned, all fasteners that penetrate the CRJ700/900/1000 fuel tanks

are wet installed. An additional brushed seal (dome sealant) is applied to the interior

end of the fastener. The application of this brushed sealant is rigorously controlled by

BAPS 157-027 “Integral Fuel Tank Sealing”. A Quality Assurance process is in place to

ensure that all the requirements from this BAPS are met.

In addition, the BAPS requires that the fuel tank sealant be leak tested per applicable

Functional Test Procedure. In order to meet the intent of the BAPS and 25.981(a)(3), a

complete wing reservoir pressure leak test is performed on every aircraft during

production, per FTER-IN670-281102. This test consists of pressurizing the complete

main wing reservoirs to 3.5 psi, including the collector bays and center reservoir for 60

minutes, to ensure no evidence of leakage. This ensures the integrity of the sealant

applied to the fasteners.

During the SFAR 88 campaign to improve fuel system safety, BA conducted inspections

of CRJ fuel tanks on in-service aircraft. It was noted that even after years of service

experience, there has been no known instance of sealant deterioration.

BA has previously presented to TCCA the use of sealant as a means of containing arcs

and sparks in order to avoid having an ignition source within the fuel tank. The fuel

access panels are attached to the wing by screws (which are non-interference fit) that

pass through a clamping ring, pass through the access panel and are held by dome

anchor nuts that are attached with rivets to the access panel (see Figure 1). During

# 13 

# zone 2A testing of the original Challenger fuel access doors, it was found that sparking

occurred at the interface of the dome anchor nuts and the rivets used to retain the dome

anchor nuts. Pictures of the sparking were recorded. The test was re-done with a new

panel where the dome anchor nuts and retaining rivets were potted with sealant. There

was no evidence of sparking or arcing during the retest. This is presented in RAE-600-

110 “CL-600 Design Compliance Aircraft Lightning Protection”. This report also contains

other examples, such as the secondary feed fuel pump where sealant was used as a

means to suppress sparking at the pump retaining fasteners and anchor nuts and rivets

of the pump box.

The test described above can be seen as an example of a lightning strike to a fastener in

an “oversized hole”. As shown in Figure 1, the minimum clearance between the screw

and the various holes is two thousandths of an inch. The primary current path is then

from the screw to the dome anchor nut to the access panel to the gasket to the wing

plank. Testing this configuration caused sparking at the interface of the dome anchor

nut rivets and the access panel. Sealant was used to contain the sparks and the re-test

was passed.

Figure 1- Fuel Access Panel Installation

4.2- Supplementary Exemption justification

Further to item 4.1 above, BA will demonstrate that the CRJ1000 design is safe and

justifies the exemption based on:

- the BA service history of Regional & Business Jet wing designs, and

- the low flammability exposure of the CRJ1000 wing fuel tank. GASKET 600-10189-1

HOLE Ø.23-.32 CLAMP RING 600-10186-1

HOLE Ø.251-.258

CSK 100° x Ø.499 OUTER DISH 600-10050-9

HOLE Ø.310 NUT PLATE NAS1473-A4

Washer in nut plate: Ø.289 MIN

Wing Plank

MS24694-S103

Screw diameter: Ø.246-249 A ccess Panel Dome Anchor Nut

# 14 

# 4.2.1- Service History

BA manufactures all Regional Jet and Challenger Business Jet wings in-house. The

processes regarding wing tank fasteners installation are the same for all of these aircraft.

Also, there have been no reported instances of loose fasteners or sealant degradation

on these aircraft, for over 17 million flying hours. This is further supported by the high

time fuel tank internal inspections performed, with Authority participation, related to the

SFAR 88 activity. No missing or damaged sealant was observed during these

inspections.

4.2.2 - Low Flammability Exposure

By definition, an aluminum wing with no significa nt internal or external heating source is

considered of low flammability. As per the definition prescribed in FAA AC 25.981-2A,

the wing design is a relatively thin design with a large surface area to volume ratio,

providing good cooling characteristics (i.e good c ooling characteristics normally result in

a surface to area volume ratio greater than 1.0; the CRJ1000 ratio is 1.7). For the center

tank, assessments were performed for FAR 26 compliance based on ground and flight

tests conducted on CRJ700 aircraft, which have similar cooling characteristics as the

CRJ1000. It has been demonstrated that the flammability exposure is less than 7%, in

accordance with the FAA Fuel Tank Flammability Assessment Model (Monte Carlo) as

per Appendix N of Part 25 and FAA AC 25.981-2A.

Ref: BA substantiating reports RAP-IN670-173 “Fuel Tank Flammability Exposure”

5 - Conclusion on the Effect on Safety

Fuel tank ignition prevention is ensured through low fuel tank flammability exposure and

the preclusion of ignition sources within t he tank. The prevention of ignition sources is

substantiated by analysis of all potential ignition sources, using the guidance of

AC25.981-1B (noting that this AC did not address the “structural lightning” aspects) and

the development of airworthiness limitations , both fuel system mandatory inspections

and by defining critical design configuration control limitations (CDCCLs). As added

safety justification, design changes requi red to show compliance with SCA H2002-03

have been accomplished. All the resulting mandatory modifications are included as an

integral part of the CRJ1000 type design. Low fuel tank flammability exposure has been

demonstrated for FAR 26.33 compliance as per FAA guidance AC 25.981-2A and Part

25 Appendix N.

BA considers the design of the CRJ1000 wing a safe design, with good service history

and meets authority expectations for an aluminum wing design. BA believes granting

this exemption has no impact on safety.

6 - What factors were considered in the determination of public interest?

In accordance with FAA policy memo ANM-112-08-002 “Lightning protection of fuel tank

structure”, compliance to 14 CFR 25.981(a)(3) with respect to lightning protection will

require the introduction of a third means of protection for the design of the CL-600-2E25

# 16 Attachment 3 to BA letter AW-CRJ/10/388 dated Jun 07, 2010



# Fuel System Memo CRJ1000/28/20 10/001/EH dated 29 March 2010.

"Memo

CRJ1000_28_2010_0

# MEMO

DATE 

# 31 March 2010

SUBJECT 

# CL-600-2E25 (CRJ1000) Fuel Tank Ignition Prevention – Aircraft

Systems; AWM 525 / 14 CFR 25.981(a)

FROM 

# Endro Haryono

TO 

# Baljeet Manhas

CC 

# Alain Loranger, Geoffrey Armstrong, Fidelio Eugenio, Guy De Langis, ,

Branko Petrovic, Peter Stoyel, Francois Hopkins, Ghislain Grenier,

James Moran, Gordon A. MacMillan, Johan Kohler

REFERENCE 

# CRJ1000/28/2010/001/EH

1. References

a. RBR-BA690-144 – Fuel Tank System Safety - Ignition Prevention Report

b. Special Condition Airworthiness (SCA) H 2002-03 - Fuel Tank System Safety - Ignition

Prevention Report

c. Policy Guidance for Fuel Tank Structural Lightning Protection Policy – Final Draft

d. RAP-IN670-173 – Fuel Tank Flammability Exposure Analysis

e. FAA approval of Bombardier CRJ Flammability Analysis Report dated 6 August 2009.

f. RAZ-BA698-017 – CL600-2E25 Wing Tank Structural Survey in Support of Compliance

with AWM 525 / 14 CFR 25.981(a)(3)

2. Background

The FAA issued a policy to determine the regulatory path of fuel tank lightning protection

(Reference 1.c). It is stated that this policy is only applicable to the fuel tank structure and does

not apply to lightning protection of the system components.

This memo outlines the safety assessment that was done on the CL-600-2D24 aircraft systems

to demonstrate compliance to SCA H2002-03 (Reference 1.b), which will also be used to show

compliance to AWM 525 / 14 CFR 25.981(a) for the CL-600-2E25.

Also, as defined in the FAA guidance, the requirement for either a special condition or

petitioning for an exemption is dependent upon fuel tank flammability exposure. Hence in

addition, this memo summarizes the CRJ1000’s fuel tank flammability exposure (Reference

1.e).

# 2 3. Fuel Tank Ignition Prevention

a. Design Changes

In general, the CRJ1000 system design is similar to the CRJ700/900. A couple of design

changes in the fuel tank or adjacent of the fuel tank were introduced. None of the changes have

a negative impact to the fuel tank ignition prevention.

The following changes will be reported in the updated RBR-BA690-144 (Reference 1.a):

i. As a result of a longer wingspan, lengthening of Slat #3 and corresponding piccolo tube by

29.5” to each wing was required.

The bleed air ducting within the center fuselage for the WAI system (LH+RH) increased in

length by approximately 56” due to the center fuselage extension. A modification of fuse to

wing bleed air duct was made to accommodate the lower wing. This change does not affect

the bleed duct length in the belly fairing area.

The new bleed duct shroud was modified from the existing CRJ700/900, which is made

from a polyamide layer impregnated with steel foil instead of silicone impregnated fibber.

The inner duct material remains as CRES 321. Bleed leak detection is routed along the

bleed duct insulation vent hole and couplings.

ii. Flux Detection Unit (FDU) is not implemented for the CRJ1000.

b. Aircraft System - Safety Assessment

The detail assessment of the aircraft syst ems is documented in the report RBR-BA690-144

(Reference 1.a), and the modifications will be addressed in a new revision to the report. The

assessment includes a list of affected system components, failure modes and potential effects

to the aircraft (Refer to Appendix A).

c. Aircraft System – Lightning and Electrostatic Discharge Protection

The system components mounted on the fuel tank structure, which may potentially cause an

ignition source (spark) if improper electrical bonding or another failure case is combined with a

lightning strike or electrostatic discharge, will be addressed separately in RAZ-BA698-017.

# 3 4. Airworthiness Limitation

Airworthiness limitation(s) would be applied to ensure that possible ignition sources in the fuel

tanks are identified and precluded by design changes or maintenance actions.

a. Critical Design Configuration Control Limitation (CDCCL)

The CDCCL list will be published as a part of the Maintenance Requirement Manual (MRM).

The CDCCL provides instructions to retain the crit ical ignition source prevention feature during

configuration changes that may be caused by component substitutions, alterations, repairs or

maintenance actions. The CRJ1000 CDCCL list would be identical to the existing CRJ700/900

(Refer to the Appendix B).

b. Fuel System Limitation (FSL)

A periodic inspection would be applied against the critical component to ensure an equivalent

level of safety. The list of component, task and interval will be published in the MRM. The

CRJ1000 FSL list would be identical to the existing CRJ700/900 (Refer to the Appendix C).

5. Fuel Tank Flammability

The CRJ1000 fuel tank flammability exposure analysis was determined based on guidance

given in FAA AC 25.981-2A and Part 25 Appendix N.

According to this method, a qualitative assessment is used to determine wing fuel tank

flammability. The center fuel tank flammability exposure was analyzed using the FTFAM/Monte

Carlo Analysis methodology as per Appendix N of Part 25.

The fuel tank flammability analysis has been completed based on aircraft test results and is

documented in RAP-IN670-173 (Reference 1.d).

a. Wing Tank

As per the criteria defined in the FAA AC 25.981-2A, it is shown that the wing main fuel tanks

are categorized as conventional aluminum with no heating source. Hence it is considered as

having low flammability. Detailed assessments are presented in the BA report RAP-IN670-173

(Reference 1.d).

# 5 

# APPENDIX A

Potential Ignition Source Hazard Assessment

(RBR-BA690-144)ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS27-601 Multi-FunctionSpoilers Wiringchaffing inconduit.All Electrical arcIgnition Sourcein Fuel Tank inthe event ofconduit burnthrough, and HotSurface Ignitionsource in FuelTank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Shielded wires inmetal conduit fromfront spar to rearspar.28-20 2 Engine FeedBoost Pumpwiring chaffing inAluminumconduit.All Electrical arcIgnition Sourcein Fuel Tank inthe event ofconduit burnthrough, and HotSurface Ignitionsource in FuelTank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Wires in metalconduit from frontspar to pumpcanister.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 3 Engine FeedBoost Pumpfailures increasingCanistertemperature >204°C.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Temperatureincrease fromlocked rotor due toFOD,protection bythermal fuse.Pump cartridgesubmerged.Qualified bysimilarity andanalysis.28-20 4 Engine BoostPump produceselectrical arcsfrom internalcomponentfailures or wirechaffing.All Electrical ArcIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridgesubmerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 5 Engine FeedBoost Pumpproduces frictionsparks frominternalcomponents.All Friction SparkIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.28-20 6 Impeller tohousing contact inBoost Pump.All Friction SparksIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 7 Ingestion of FODin Boost PumpImpeller.All Friction SparksIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.28-20 8 FOD Ingestion orcomponentfailures causingBoost PumpMotor to stallheating windings>204°C.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.Qualified by test andanalysis.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 9 APU Fuel Pumpfailures increasingCanistertemperature >204°C.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Temperatureincrease fromlocked rotor due toFOD, protection bythermal fuse.Pump cartridgesubmerged.Qualified bysimilarity andanalysis.28-20 10 APU Fuel Pumpproduceselectrical arcsfrom internalcomponentfailures or wirechaffing.All Electrical ArcIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridgesubmerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 11 APU Fuel BoostPump producesfriction sparksfrom internalcomponents.All Friction SparkIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.28-20 12 Impeller tohousing contact inAPU Fuel Pump.All Friction SparksIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 13 Ingestion of FODin APU FuelPump Impeller.All Friction SparksIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge &impeller submerged.28-20 14 Fuel TransferSOV body heating>204°C.All Hot SurfaceIgnition source inFuel TankFAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Qualified bysimilarity andanalysis.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 15 Cross-Flow PumpFailuresincreasingTemperature>204°C.All Hot SurfaceIgnition Sourcein TankFAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Temperatureincrease fromlocked rotor due toFOD. Protectioncarried out bythermal Fuses.Pump Cartridgesubmerged.28-20 16 Cross-Flow Pumpproduceselectrical arcsfrom internalcomponentfailures or wiringchaffing.All Electrical ArcIgnition source infuel tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridgesubmerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 17 Cross-Flow Pumpproduces frictionsparks frominternalcomponents.All Friction SparkIgnition Sourcein fuel tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge andimpeller submerged.28-20 18 Ingestion of FODin Cross-FlowPump Vaneelements.All Friction SparkIgnition Sourcein fuel tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge andimpeller submerged.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 19 FOD ingestion ofcomponentfailures causingCross-Flow Pumpmotor to stall,heating winding>204°C.All Hot SurfaceIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.QualificationTesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Pump cartridge andimpeller submerged.28-20 20 Gravity TransferSOV motorheating >204°C.FLT Hot SurfaceIgnition source inFuel Tankthrough Fuel tankwall.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.QualificationTesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Low operatingcurrent (1.5 A).Qualified explosionproof.In order for fuel toget in the actuator,two seals must bedamaged (one in thevalve body and onein the actuator).Same actuator isused to drive theball valve of theAPU and engineSOVs. Therefore theassessment isapplied to the engineand APU SOV.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-20 21 Refuel DefuelSOV Solenoidheating >204°C.GND Hot SurfaceIgnition source inRefuel/DefuelManifoldHousing.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.QualificationTesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Low operatingcurrent (0.5 A).28-40 22 Fuel QuantityGaugingComputer failurecausing highenergy output toFuel QuantityProbes.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-40 23 Fuel Quantitygauging wiringchaffing withpower wiringcausingcapacitance probediode heating>204°C.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Qualificationtesting.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Fuel Qty gaugingwires are in thesame harness as thefuel temperaturesensor wires andhigh level sensorwires and aresegregated fromother aircraft wires.HLS and gaugingprobes are energizedwith 28V whiletemperature sensoris energized withlow voltage fromDCU.28-40 24 Fuel Quantitygauging wiringchaffing withpower wiringcausing electricaldischarge acrossgap.All Electrical ArcIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Fuel Qty gaugingwires are in thesame wiring harnessas the fueltemperature sensorwires and high levelsensor wires and aresegregated fromother aircraft wires.HLS and gaugingprobes are energizedwith 28V whiletemperature sensoris energized withlow voltage fromDCU.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-40 25 Fuel Quantitygauging wiringchaffing in tank.All Electrical ArcIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.28-40 26 Fuel TemperatureProbes wiringchaffing withhigh-energywiring resulting inprobe heating to>204°C.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Fuel Qty gaugingwires are in thesame wiring harnessas the fueltemperature sensorwires and high levelsensor wires and aresegregated fromother aircraft wires.HLS and gaugingprobes are energizedwith 28V whiletemperature sensoris energized withlow voltage fromDCU.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-40 27 High LevelSensor Probeglass bead failure.All Filament HeatingIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Powered duringcentre tank to maintank transfer.28-40 28 High LevelSensor Probeglass bead heats>204°C fromwiring chaffingwith high-energywiring.All Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Powered duringcentre tank to maintank transfer.Fuel Qty gaugingwires are in thesame wiring harnessas the fueltemperature sensorwires and high levelsensor wires and aresegregated fromother aircraft wires.HLS and gaugingprobes are energizedwith 28V whiletemperature sensoris energized withlow voltage fromDCU.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS28-40 29 Pressure Sensordiaphragm failureresulting inmicroswitch andwiring exposureto vapor.All Electrical ArcIgnition Sourcein Fuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.28-40 30 Scavenge EjectorDelta-P SensorSwitch heats>204°C fromwiring chaffingwith high-energywiring.GND Hot SurfaceIgnition source inFuel Tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS29-00 31 Hydraulic FluidOverheat >204°Cin hydraulic linespassing throughfuel tanks.All Hot surfaceIgnition source infuel tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Thermal Analysisand tests.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.33-40 32 Landing and TaxiLightscompartmenttemperature heatswing tank surface>204°C.GND Hot surfaceIgnition source infuel tank.FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Thermal Analysis.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.Landing and taxilights are 13 inchesin front of the frontspar. In addition,maximumtemperature of thelights is 97°C.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS36-10 33 Bleed duct leakover centre fueltank heatingcentre tanksurface>204°C.All Hot surfaceIgnition source infuel tank.FAR 25.901FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Thermal Analysis.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.There is a thermalblanket between theAnti-Ice pipes andthe top of the centretank.The CRJ1000 bleedduct configurationrunning over thecenter tank ismodified fromCRJ700/900. Theshroud is made frompolymide layerimpregnated with asteel foil instead ofsilicone impregnatedfiber.The main bleed ductis stainless steel(CRES 321). Bleedleak detection isrouted along thebleed duct insulationvent hole andcouplings.ATA ITEMNOHYPOTHETICALCOMPONENTFAILUREFLIGHTPHASEPOTENTIALEFFECT ONAIRCRAFTREQUIREMENT METHOD OFEVALUATIONASSESSMENTREPORTSECTIONREMARKS36-10 34 Anti-Ice ductoverheat heatingfront sparsurface>204°C.All Hot surfaceIgnition source infuel tank.FAR 25.901FAR 25.981FAR 25.1309Fuel Tank SystemSafety Review.Thermal analysis.RBR-BA690-144The appropriatesections of thereport will beupdated to showcompliance forCRJ1000.The updated reportwill be submittedas part of basictype certification.The CRJ1000 bleedduct connects thefuselage to the wingand passing by thefront spark ismodified fromCRJ700/900. Theshroud is made frompolymide layerimpregnated with asteel foil instead ofsilicone impregnatedfiber.The main bleed ductis stainless steel(CRES 321). Bleedleak detection isrouted along thebleed duct insulationvent hole andcouplings.Anti-Ice duct is inthe inboard leadingedge area andconnected to the slatvia the telescopicduct.

# 6 

# APPENDIX B

Critical Design Configurati on Control Limitation (CDCCL)

Maintenance Requirement Manual (MRM) CSP B-053AIRWORTHINESS LIMITATIONSTEMPORARY REVISION 2−268Date: Dec 18/08Airworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 − Fuel System LimitationsTR 2−268Page 2 of 2Table 1 − List of Critical Design Configuration Control Limitations (CDCCL)CDCCL ITEMSCRITICAL IGNITION PREVENTION FEATUREMANUAL REFERENCEAPPLICABILITYPink striped protectivesleevesor,Production − Pink WireJacket W22 CodeChaffing of Gauging wire with power wires causing fuelprobe overheatWDM 28−40−00SB 670BA−24−011Front spar wire clippingfailure inspectionChaffing of Gauging wire with power wires causing fuelprobe overheatAMM 24−90−00−220−801SB 670BA−24−012Self−bonding couplings infuel tanks. P/ N 14J26,LC459Bonding of fuel and vent lines for lightning protectionAMM 51−80−00−760−802SB 670BA−28−014LRU Sealant inspectionPreventing arc forming in gaps due to lightningAMM 28−00−00−220−801ALL AIRCRAFTThermal Fuse assembly onHydraulic System #1 and#2Preventing Hydraulic System overheat by dumpinghydraulic fluid overboard before it reaches the Fuel Tankauto−ignition temperatureAMM 29−11−14−961−801SB 670BA−29−005CL 600 2C10, CL 600 2D15, CL 600 2D24

# 7 

# APPENDIX C

Fuel System Limitation (FSL)

Maintenance Requirement Manual (MRM) CSP B-053TASKNUMBERTASK CODE/TASK TITLE/TASK DESCRIPTIONLIMITINGINTERVALFUEL SYSTEM LIMITATIONSMODELEFFECTIVITYAMTOSSAIRWORTHINESS LIMITATIONSBCL-600-2C10, CL-600-2D15 and CL-600-2D2424-90-00-60120000 Flight HoursFUEL TANK WIRING HARNESS INSTALLATION: Detail Inspectionof the fuel tank wiring harness installation in the fuselage forcondition and security.24-90-00-220-802All24-90-00-60220000 Flight HoursFUEL TANK WIRING HARNESS INSTALLATION: Detail inspectionof the fuel tank wiring harness installation at the center tankfront spar for condition and security.24-90-00-220-801All28-00-00-60120000 Flight HoursFUEL TANK LINE REPLACEABLE UNIT SEALANT: DetailInspection of all the fuel Tank LRUs to ensure the condition andintegrity of the sealant around their mounting surfaces andattachments.28-00-00-220-801All28-11-23-60120000 Flight HoursFUEL STOWAGE SYSTEM PIPE: Functional check toensure thatthe electrical bonding values of the Fuel Stowage System PipeAssy`s is within tolerannce.28-11-23-720-801All28-11-23-60220000 Flight HoursFUEL STOWAGE SYSTEM PIPE BONDING JUMPER: Detailinspection of the Fuel Stowage System Pipe Bonding Jumpers forcondition and security.28-11-23-220-801All28-12-13-60120000 Flight HoursCLIMB VENT LOOP BOOT ASSEMBLY AND DRAINAGE TUBE:Detail inspection of the climb vent loop boot assy`s and drainagetubes for condition and security.28-12-13-220-801All29-30-00-6018000 Flight HoursHYDRAULIC SYSTEM # 3 TEMPERATURE TRANSDUCER:Operational check of the Hydraulic System # 3 TemperatureTransducer via EICAS29-36-00-710-801All29-30-00-60230000 Flight HoursHYDRAULIC SYSTEM # 3 TEMPERATURE TRANSDUCER:Discard the Hydraulic System # 3 Temperature Transducer29-36-03-961-801AllAirworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 - Fuel System LimitationsPage 2 - 3 - 5Revision: 10Revision Date: Mar 20/2008See Effective TRTEMPORARY REVISION 2−269The contents of this Temporary Revision have been approved by the Chief, Engineering (or designate), National Aircraft Cerification Branch, TransportCanada Civil AviationDate October 10, 2008Signed Roop DhaliwalFILING INSTRUCTIONS:Insert this Temporary Revision (TR) 2−269 facing page 2−3−5 in Part 2 of the Maintenance RequirementsManual.Record the incorporation of this Temporary Revision on the yellow RECORD OF TEMPORARY REVISIONSsheet at the front of this Part.Keep this Temporary Revision until normal revision service incorporates this information into the MaintenanceRequirements Manual.DESCRIPTION:To add TASK NUMBER 29−30−00−603.TASKNUMBERMODELEFFECTIVITYAMTOSSTASK CODE/TASK TITLE/TASK DESCRIPTIONLIMITINGINTERVAL29−30−00−603ALL29−11−14−961−801HYDRAULIC SYSTEM #1 and #2 THERMAL FUSE: Discard thesystem #1 and #2 thermal fuse (Post Modsum 670T112042 or SB670BA−29−005)10000 Flight HoursCL−600−2C10, CL−600−2D15 AND CL−600−2D24AIRWORTHINESS LIMITATIONSAirworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 − Fuel System LimitationsPage 1 of 1TR 2−269Date: Dec 18/2008CL 600 2C10, CL 600 2D15, CL 600 2D24

# 17 Attachment 4 to BA letter AW-CRJ/10/388 dated Jun 07, 2010



# EMC memo CRJ900-01-66-2010-26 dated March 29, 2010

"EMC Memo for

25-981a3 Complianc e

# BT0043-02 MW97 2001-09 

# 2 1. References

1.1. AWM 525.981(a)(3)

1.2. FAR 25.981(a)(3)

1.3. TCCA document Fuel System Lightning Protection Certification Areas of Discussion

Revised 1/27/10

1.4. FAA draft document Policy Guidance for Fuel Tank Structural Lightning Protection

Policy

1.5. TCCA Issue Paper AV-1

1.6. RAZ-BA698-017 CL-600-2E25 Wing Tank Structural Survey in Support of Compliance

with AWM 525 / 14 CFR 25.981(a)(3)

2. Discussion

As discussed with representatives of TCCA a nd FAA at the 24 September, 2009 meeting in

Montreal, BA is taking a three phase approach to provide the required supporting data for the

request for partial exemption from 25.981(a)(3). Thus far, Phase 1 and 2 have been completed.

The purpose of this memo is to document th e approach that will be used for Phase 3.

Phase 1 consisted of defining the structural failure modes that are possible within the wing tank.

Phase 1 was completed with the issue of RAZ-BA698-017 Rev --. Phase 2 consisted of an

assessment of the structural failure modes identifie d in Phase 1 to determine which could result in

a potential ignition source in the event of a lightning strike and of these, which were fault tolerant

or not fault tolerant. Phase 2 was completed with the issue of RAZ-BA698-017 Rev A which was

subsequently updated to Rev B to incorporate TCCA comments.

The plan for Phase 3 is as follows:

A) For all fault tolerant features:

1. Determine all test data that is required to s ubstantiate the request for partial exemption.

In particular, test data is re quired to demonstrate the fault tolerance of structural features 1



# .

2. Determine from this set of required test data , what testing has already been conducted as

part of previous certification efforts and wh at data must be collected through additional

testing. This will be discussed and agreed with the certification authorities before

proceeding.

3. Prepare test plans and test articles that will be used to provide the missing required data.

4. Conduct lightning certification testing on these test articles that will be witnessed by the

certification authorities.

# BT0043-02 MW97 2001-09 

# 3 5. Document all findings and assessment and present the results to the certification

authorities.

At this time, the exact test articles of fault tolera nt features are yet to be defined. However, they

will cover all cases documented in RAZ-BA698-017 Re v A/B. Some examples of possible test

articles to show fault tolerance are:

• an interference fit fastener installed with the interference fit degraded (e.g. in an

oversized or double hole) which has the brush sealant installed over the collar

• an interference fit fastener with a gap between the collar and the structure (e.g.

due to hole drilled at an angle or grip le ngth that is too long) which has the brush

sealant installed over the collar

• a fuel access panel with the electrical bonding area degraded

These tests will be performed according to the test methods and waveforms of SAE ARP 5416

and 5412A. The test articles will be monitored du ring the tests for possible ignition sources (i.e.

sparking, arcing, hotspots, etc).

B) For all non-fault tolerant features:

1. Conduct an assessment to determine if it is practical to introduce additional protection.

2. If it is not practical, conduct an assessment to show that the fuel tank design meets the

safety requirements.

3. If it is practical, introduce additional protective features and provide the required test data

to substantiate fault tolerance.

4. Document all findings and assessment and present the results to the certification

authorities.

C) For features where fault tolerance is to be determined:

1. Determine fault tolerance status through testing.

2. Proceed as per A) or B) above depending on outcome of above testing.

It is estimated that approximately 144 1 

# test articles will be required (the Policy Guidance for Fuel

Tank Structural Lightning Protection Policy recommends several test articles for each test case).

The total estimated length of the test campaign including preparation of test plans, definition of

test articles, construction of the test articles, tes ting, and preparation/review of the test results is

approximately thirty 1 

# months. Concurrent with the test campaign, the analysis work required for

non-fault tolerant features would be conducted. It is estimated that the analysis work will be

completed by the time the test campaign has wrappe d up, thus allowing the entirety of Phase 3 to

be completed in the fourth quarter of 2012 1



# .

# BT0043-02 MW97 2001-09 

# 4 Upon completion of Phase 3, report RAZ-BA698-017 shall be updated to include discussion of

the test and analysis results. Additionally, an y affected DCRs shall also be updated with the

necessary information.

Notes:

1. The memo was updated to revision A to inco rporate the updated estimates of the number of

test articles and the length of the test campa ign based upon discussions between BA and TC on

27 April and 6 May 2010. Specifically, the change was required due to the fact that lightning

Zone 3 and internal features are to be considered for fault tolerance in addition to lightning Zone

2A. All changes are marked with change bars.

# 18 Attachment 5 to BA letter AW-CRJ/10/388 dated Jun 07, 2010



# RMAS Memo: Procedure for the Nu merical Probability Assessment of

the CRJ-1000 Fuel Tank Structural Non-Fault Tolerant Feature

Failures, dated March 29, 2010.

"RMAS MEMO Fu e

T ank Lightning Pr o

# MEMO

DATE 

# March 29, 2010

SUBJECT 

# Procedure for the numerical probability assessment of the CRJ-1000

fuel tank structural Non-Fault Tolerant Feature Failures

FROM 

# Z. Klim, J-P. Dargis

TO 

# B. Manhas

CC 

# R. Heppell

Reference:

1. Policy Guidance for Fuel Tank Structural Lightning Protection Policy, 2010

2. RAZ-BA698-017, Rev.A, Wing Tank Structural Survey in Support with Compliance with

AWM525 /14CFR 25.981(a) (3)



# 1. Introduction

This Memo provides BA approach to establish compliance with current regulatory standards

applicable to lightning protection of the CRJ-1000 fuel tank structure for Non-Fault Tolerant

Feature Failures by numerical probability assessment. The proposed procedure is using the

criteria defined in the FAA Policy Guidance for Fuel Tank Structural Lightning Protection Policy

(ref.1) and is aligned with the regulatory path described as petitioning for an exemption.

For areas of the design where it is found to be impractical to provide fault tolerance, the required

numerical probability assessment will be conducted to ensure a fuel vapor ignition is extremely

improbable. An extremely improbable probability is described in AC 25.981-1C as failure

conditions so unlikely that they are not anticipated to occur during the entire operational life of

all airplanes of one type. Numerically this is defined to be less than 1 x 10 -9 

# events per flight

hour. The purpose of the assessment is to substantiate that the probability of failures associated

with non-fault tolerant features that might lead to a fuel tank explosion is in extremely

improbable category.



# 2. General Approach to the Numerical Probability Assessment

The relevant non-fault tolerant structural design areas that may contribute to ignition sources

inside the fuel tank when a failure occurs will be identified. Each type of non-fault tolerant

feature failure will be assessed and the result will be summed.

Once the non-fault tolerant feature failure (NFTFF) types are identified, their failure rates will be

determined using the available data. Some additional factors might be considered when

# 2 determining failure rates including the configuration or design specific details as described in the

Policy.

The main steps of the process leading to the identification and numerical probability assessment

of the NFTFFs are described below:

1. Identify potential failure modes

2. Assess failure condition

3. Determine fault tolerance

4. Determine practicality of providing fault tolerance

The set of the potential failure modes regardless of the probability of occurrence was

established by performing a complete wing tank su rvey in pertinent areas related to fuel tank

lightning protection as defined FAA “Policy Guidance for Fuel Tank Structural Lightning

Protection”(ref.1). If the failure assessment result s in demonstrating that the design is free from

ignition sources after assessment of relevant single failure conditions, then the design is

considered to be fault tolerant. If not, then further analysis is required per numerical probability

assessment for the Non-Fault Tolerant Feature Failures. The subset of NFTFFs was defined

and the numerical probability assessment will be performed according to the guideline provided

in section 3.5 of the Policy.



# 3. Numerical Probability Assessment

The purpose of this assessment is to substantiate that it is extremely improbable that failures

associated with non-fault tolerant features will lead to a fuel tank explosion. The sample fault

tree diagram in Figure 1 provides an example of a fault logic structure that will be used for

conducting this numerical assessment. Basic ev ents are user supplied probability inputs, which

will be assessed based on the available data, tests and recommendation from the Policy. After

that, these probabilities will be multiplied together when linked by an “AND” gate or summed

together when linked by an “OR” gate. The relevant non-fault tolerant structural design areas

that may contribute to ignition sources inside the fuel tank when a failure occurs will be

identified. Each type of non-fault tolerant feature failure will be assessed and the result

summed. To be compliant, the top-level event must result in a numerical value less than 1 x 10 -9



# events per flight hour. The steps related to the probability inputs assessment and analyses are

described below.

# 3 Figure 1 – Procedure of the analysis for numerical probability assessment of the NFTFFs

Step 1 – probability of lightning attachment to aircraft per flight hour will be assessed based on

the available data and the recommendation from the Policy. According to the AC20-155 and

ARP5412A the probability of lightning attachment to aircraft vary between 1/1000 and 1/20 000.

Nominal probability is considered to be: 1/3000. Therefore the probability of 3E-4 can be used 3.11

Overall

Probability

of Fuel Vapor

Ignition Event

3.9

Overall Spark

Probability at

NFTFF1 3.10

Fleet Average

Flammability

Exposure

(FEET)

3.7/3.9

Failure

Probability of

NFTFF1

Factor for

Current

Exceeding

Sparking

Threshold for

NFTFF1 Probability of

Vapor Ignition due

to Non-Fault

Tolerant Feature

Failure 1

(NFTFF1)

3.9

Current

Exceeds

Sparking

Threshold at

NFTFF1 Probability of

Vapor Ignition due

to Non-Fault

Tolerant Feature

Failure 2

(NFTFF2)

Overall

Probability

of Attachment to

General Area of

NFTFF1

Probability of

Lightning

Attachment to

Aircraft Per

Flight Hour Distribution

Factor for

Attachment to

General Area of

NFTFF1 Probability of

Vapor Ignition due

to Non-Fault

Tolerant Feature

Failure 3

(NFTFF3) 

# Criteria: Overall Probability of

Fuel Vapor Ignition Event ≤ 1E-9

Typically 3E-4 See Table 3.9-1 See Figures 3.9-1

and 3.9-2



# 1 2 3 4 5 6

# 4 for the purpose of this analysis as recommended by the Policy. BA field data will be used also to

assess this probability.

Step 2 – distribution factor for attachment to general area of the aircraft will be obtained by

combining the probability of lightning attachment to an aircraft with a distribution of initial

lightning attachment locations on an aircraft (i.e. the percentage of lightning attachments to

initial entry and exit locations). While there can be several possible combinations of initial

lightning entry and exit locations per lightning strike event, for purpose of this analysis only one

set of initial lightning attachment locations (i.e. one “entry” and one “exit” point) will be assumed.

The distribution of initial attachment locations will be obtained from manufacturers’ data or the

generic numbers as provided in Table 3.9-1 of the Policy.

Step 3 – factor for current exceeding sparking threshold in a joint that would potentially cause

an ignition source given a failure condition will be established. While there are various lightning

current components and energy parameters that can influence ignition sources, for this

numerical probability assessment it is acceptable to simplify things by using a peak stroke

current distribution for the lightning threat exceedance curves. Acceptable peak current

distributions for Zone 1 and Zone 2 threats are provided in Figures 3.9-1 and 3.9-2 (ref.1). The

ignition source (sparking) threshold data (kA) will be determined using test objects containing

the fastened or bonded joint with the failure condition implemented. The result of this activity will

be amplitudes of direct strike or conducted lightning currents in kiloamperes (kA) that are the

maximum levels where ignition sources should not occur under specific failure conditions. This

ignition source threshold must be compared with results of analysis to determine what

conducted current levels are expected at non-fault tolerant features. The exceedance probability

results are based upon the ratio of the sparking threshold over joint current conducted by the

fastener to interior structure and scaling by a full threat stroke current factor. The exceedance

probability value will be taken from Figure 3.9-1 or Figure 3.9-2 for the respective zones.

Step 4 – failure probability of NFTFF will be determ ined using all available data from the field.

Numerical analysis methods and engineering judgment will be used to estimate these failure

rates based on conservative assumptions. For most structural lightning protection features, the

failure modes are latent which means that once failed they will be failed until repaired or until the

end of the airplane life. The NFTFF average probability of failure will be considered for latent

failure modes and normalized value per flight hour will be used in the probability calculation as

recommended by the Policy.

Step 5 – fleet average flammability exposure is defined as a percentage of the total flight time,

including from preflight through disembarking and unloading cargo, that the fuel tank is

considered flammable. According to the Policy for existing type certificated aircraft with a

passenger capacity of 30 or more or a payload capacity of 7500 pounds or more subject to the

provisions of 14 CFR Part 26, it is permissible to utilize the value of 7% as a default flammability

exposure for those applicants not otherwise required to meet the requirements of Appendix M