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 was 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 Requirements 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 Pro

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

APR. 2010 SEP. 2012

0. BA/TC/FAA TECHNICAL AGREEMENT 50% 26-Apr-10 28-May-10

0.1 100% 26-Apr-10 7-May-100.2 0% 7-May-10 28-May-10

1. TEST CONFIGURATION & TEST PLAN 28-May-10 15-Nov-10

1.1 0% 28-May-10 28-Jul-101.2 0% 15-Aug-10 30-Aug-101.3 0% 6-Sep-10 10-Sep-101.4 0% 15-Sep-10 15-Dec-101.5 0% 15-Aug-10 30-Sep-101.6 0% 4-Oct-10 8-Oct-101.7 0% 11-Oct-10 15-Oct-101.8 0% 15-Oct-10 15-Nov-10

2. BAEX ACTIVITIES - TEST ARTICLES 15-Dec-10 5-Oct-11

2.1 0% 15-Dec-10 15-Sep-112.2 0% 15-Sep-11 30-Sep-112.3 0% 1-Oct-11 5-Oct-11

3. LIGHTNING TESTS 15-Oct-11 30-Jan-12

3.1 0% 15-Oct-11 15-Jan-123.2 0% 15-Jan-12 30-Jan-12

4. ANALYZE/GATHER DATA 15-Mar-12 15-May-12

4.1 0% 15-Mar-12 19-Mar-124.2 0% 19-Mar-12 15-May-12

5. REPORTS & APPROVAL 15-May-12 15-Sep-12

5.1 0% 15-May-12 30-May-125.2 0% 15-May-12 15-Jul-125.3 0% 30-May-12 15-Sep-12

6. TC Commitment APR. 2010 SEP. 2012

Task completedTask late

TC to review/approve BA submitted reports i.e. Test reports (submitted end of May 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 readiness review 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) & pass fail 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 TC BA EMC to create "paper " test articles with parts lists & test configurations

PHASE 3 PLAN for 25.981(a)(3) EXEMPTION - EMC PROJECT PLAN DEC. 

2

% Complete Start Date End Date

BA EMC to present technical approach to TC

 25.981(a)(3) EXEMPTION - EMC MILESTONES

B 

Completed

25.981(a)(3) Exemption - EMC Project Plan.xls 
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 extremely improbable. It will also be shown via 

Analysis that regular inspections (where practical) 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 ignition 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 installation 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 lead 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 contact 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

Access 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 significant 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 cooling 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 the 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 required 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 CRJ1000/28/2010/001/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) H2002-03 - 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 systems 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 critical 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 ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

27-60 1 Multi-Function 

Spoilers Wiring chaffing in conduit. 

All Electrical arc 

Ignition Source in Fuel Tank in the event of conduit burn through, and Hot Surface Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 2 Engine Feed 

Boost Pump wiring chaffing in Aluminum conduit. 

All Electrical arc 

Ignition Source in Fuel Tank in the event of conduit burn through, and Hot Surface Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 3 Engine Feed 

Boost Pump failures increasing Canister temperature > 204°C. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 4 Engine Boost 

Pump produces electrical arcs from internal component failures or wire chaffing. 

All Electrical Arc 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 5 Engine Feed 

Boost Pump produces friction sparks from internal components. 

All Friction Spark 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 6 Impeller to 

housing contact in Boost Pump. 

All Friction Sparks 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 7 Ingestion of FOD 

in Boost Pump Impeller. 

All Friction Sparks 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 8 FOD Ingestion or 

component failures causing Boost Pump Motor to stall heating windings >204°C. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 9 APU Fuel Pump 

failures increasing Canister temperature > 204°C. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 10 APU Fuel Pump 

produces electrical arcs from internal component failures or wire chaffing. 

All Electrical Arc 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 11 APU Fuel Boost 

Pump produces friction sparks from internal components. 

All Friction Spark 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 12 Impeller to 

housing contact in APU Fuel Pump. 

All Friction Sparks 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 13 Ingestion of FOD 

in APU Fuel Pump Impeller. 

All Friction Sparks 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 14 Fuel Transfer 

SOV body heating >204°C. 

All Hot Surface 

Ignition source in Fuel Tank 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 15 Cross-Flow Pump 

Failures increasing Temperature >204°C. 

All Hot Surface 

Ignition Source in Tank 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 16 Cross-Flow Pump 

produces electrical arcs from internal component failures or wiring chaffing. 

All Electrical Arc 

Ignition source in fuel tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 17 Cross-Flow Pump 

produces friction sparks from internal components. 

All Friction Spark 

Ignition Source in fuel tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 18 Ingestion of FOD 

in Cross-Flow Pump Vane elements. 

All Friction Spark 

Ignition Source in fuel tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 19 FOD ingestion of 

component failures causing Cross-Flow Pump motor to stall, heating winding >204°C. 

All Hot Surface 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification Testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-20 20 Gravity Transfer 

SOV motor heating >204°C. 

FLT Hot Surface 

Ignition source in Fuel Tank through Fuel tank wall. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification Testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-20 21 Refuel Defuel 

SOV Solenoid heating >204°C. 

GND Hot Surface 

Ignition source in Refuel/Defuel Manifold Housing. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification Testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-40 22 Fuel Quantity 

Gauging Computer failure causing highenergy output to Fuel Quantity Probes. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-40 23 Fuel Quantity 

gauging wiring chaffing with power wiring causing capacitance probe diode heating >204°C. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Qualification testing. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-40 24 Fuel Quantity 

gauging wiring chaffing with power wiring causing electrical discharge across gap. 

All Electrical Arc 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-40 25 Fuel Quantity 

gauging wiring chaffing in tank. 

All Electrical Arc 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-40 26 Fuel Temperature 

Probes wiring chaffing with high-energy wiring resulting in probe heating to >204°C. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-40 27 High Level 

Sensor Probe glass bead failure. 

All Filament Heating 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-40 28 High Level 

Sensor Probe glass bead heats >204°C from wiring chaffing with high-energy wiring. 

All Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

28-40 29 Pressure Sensor 

diaphragm failure resulting in microswitch and wiring exposure to vapor. 

All Electrical Arc 

Ignition Source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

28-40 30 Scavenge Ejector 

Delta-P Sensor Switch heats >204°C from wiring chaffing with high-energy wiring. 

GND Hot Surface 

Ignition source in Fuel Tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

29-00 31 Hydraulic Fluid 

Overheat >204°C in hydraulic lines passing through fuel tanks. 

All Hot surface 

Ignition source in fuel tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Thermal Analysis and tests. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 

33-40 32 Landing and Taxi 

Lights compartment temperature heats wing tank surface >204°C. 

GND Hot surface 

Ignition source in fuel tank. 

FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Thermal Analysis. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

36-10 33 Bleed duct leak 

over centre fuel tank heating centre tank surface>204°C. 

All Hot surface 

Ignition source in fuel tank. 

FAR 25.901 FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Thermal Analysis. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
ATA ITEM 

NO 

HYPOTHETICAL COMPONENT FAILURE 

FLIGHT PHASE 

POTENTIAL EFFECT ON AIRCRAFT 

REQUIREMENT METHOD OF 

EVALUATION 

ASSESSMENT REPORT SECTION 

36-10 34 Anti-Ice duct 

overheat heating front spar surface>204°C. 

All Hot surface 

Ignition source in fuel tank. 

FAR 25.901 FAR 25.981 FAR 25.1309 

Fuel Tank System Safety Review. Thermal analysis. 

RBR-BA690-144 The appropriate sections of the report will be updated to show compliance for CRJ1000. The updated reporwill be submitted as part of basic type certification. 
6 

APPENDIX B 

Critical Design Configuration Control Limitation (CDCCL) 

Maintenance Requirement Manual (MRM) CSP B-053 
AIRWORTHINESS LIMITATIONS

TEMPORARY REVISION 2−268

Airworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 − Fuel System Limitations

Table 1 − List of Critical Design Configuration Control Limitations (CDCCL)

CDCCL ITEMS CRITICAL IGNITION PREVENTION FEATURE MANUAL REFERENCE 

Pink striped protectivesleevesor,Production − Pink WireJacket W22 Code

Chaffing of Gauging wire with power wires causing fuelprobe overheat

WDM 28−40−00 

Front spar wire clippingfailure inspection

Chaffing of Gauging wire with power wires causing fuelprobe overheat

AMM 24−90−00−220−80

Self−bonding couplings infuel tanks. P/ N 14J26,LC459

Bonding of fuel and vent lines for lightning protection AMM 51−80−00−760−802 

LRU Sealant inspection Preventing arc forming in gaps due to lightning AMM 28−00−00−220−80Thermal Fuse assembly onHydraulic System #1 and#2

Preventing Hydraulic System overheat by dumpinghydraulic fluid overboard before it reaches the Fuel Tankauto−ignition temperature

AMM 29−11−14−961−80

CL 600 2C10, CL 600 2D15, CL 600 2D24
7 

APPENDIX C 

Fuel System Limitation (FSL) 

Maintenance Requirement Manual (MRM) CSP B-053 
TASK

NUMBER

TASK CODE/

TASK TITLE/

TASK DESCRIPTION

FUEL SYSTEM LIMITATIONS

MODEL

EFFECTIVITY AMTOSS

CL-600-2C10, CL-600-2D15 and CL-600-2D24

AIRWORTHINESS LIMITATIONS

B

24-90-00-601 FUEL TANK WIRING HARNESS INSTALLATION: Detail Inspection 

of the fuel tank wiring harness installation in the fuselage for condition and security.

All 24-90-00-220-802

24-90-00-602 FUEL TANK WIRING HARNESS INSTALLATION: Detail inspection 

of the fuel tank wiring harness installation at the center tank front spar for condition and security.

All 24-90-00-220-801

28-00-00-601 FUEL TANK LINE REPLACEABLE UNIT SEALANT: Detail 

Inspection of all the fuel Tank LRUs to ensure the condition and integrity of the sealant around their mounting surfaces and attachments.

All 28-00-00-220-801

28-11-23-601 FUEL STOWAGE SYSTEM PIPE: Functional check to ensure that 

the electrical bonding values of the Fuel Stowage System Pipe Assy`s is within tolerannce.

All 28-11-23-720-801

28-11-23-602 FUEL STOWAGE SYSTEM PIPE BONDING JUMPER: Detail 

inspection of the Fuel Stowage System Pipe Bonding Jumpers for condition and security.

All 28-11-23-220-801

28-12-13-601 CLIMB VENT LOOP BOOT ASSEMBLY AND DRAINAGE TUBE: 

Detail inspection of the climb vent loop boot assy`s and drainage tubes for condition and security.

All 28-12-13-220-801

29-30-00-601 HYDRAULIC SYSTEM # 3 TEMPERATURE TRANSDUCER: 

Operational check of the Hydraulic System # 3 Temperature Transducer via EICAS

All 29-36-00-710-801

29-30-00-602 HYDRAULIC SYSTEM # 3 TEMPERATURE TRANSDUCER: 

Discard the Hydraulic System # 3 Temperature Transducer

All 29-36-03-961-801

Airworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 - Fuel System Limitations

See Effective TR
TEMPORARY REVISION 2−269

The contents of this Temporary Revision have been approved by the Chief, Engineering (or designate), National Aircraft Cerification Canada Civil AviationDate October 10, 2008 Signed Roop Dhaliwal

FILING INSTRUCTIONS: Insert this Temporary Revision (TR) 2−269 facing page 2−3−5 in Part 2 of the Maintena

Manual.Record the incorporation of this Temporary Revision on the yellow RECORD OF TEMPsheet at the front of this Part.Keep this Temporary Revision until normal revision service incorporates this informatioRequirements Manual.

DESCRIPTION: To add TASK NUMBER 29−30−00−603.

TASK

NUMBER

MODEL

EFFECTIVITY AMTOSS

TASK CODE/

TASK TITLE/

TASK DESCRIPTION

29−30−00−603 ALL 29−11−14−961−801 HYDRAULIC SYSTEM #1 and #2 THERMAL FUSE: Discard the

system #1 and #2 thermal fuse (Post Modsum 670T112042 or S670BA−29−005)

CL−600−2C10, CL−600−2D15 AND CL−600−2D24

AIRWORTHINESS LIMITATIONS

Airworthiness LimitationsPart 2 of Maintenance Requirements ManualSection 3 − Fuel System Limitations

CL 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 Compliance

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 and 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 the 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 identified 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 substantiate the request for partial exemption. 

In particular, test data is required to demonstrate the fault tolerance of structural features1

. 

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

part of previous certification efforts and what 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 tolerant features are yet to be defined. However, they 

will cover all cases documented in RAZ-BA698-017 Rev 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 length 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 during 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 1441

 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, testing, and preparation/review of the test results is 

approximately thirty1

 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 wrapped up, thus allowing the entirety of Phase 3 to 

be completed in the fourth quarter of 20121

. 
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, any affected DCRs shall also be updated with the 

necessary information. 

Notes: 

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

test articles and the length of the test campaign 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 Numerical Probability Assessment of 

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

Failures, dated March 29, 2010. 

"RMAS MEMO Fue

Tank Lightning Pro
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 survey 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 results 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 events 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 determined 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