AEROSPACE

Bombardier Inc. 400 chemin de la Côte-Vertu

West Dorval, Québec, Canada H4S 1Y9
www.bombardier.com

TEL 514-855-5000

F AX 5 14

- 855-8436 2016-02-18

AW/BD5/16/073

Subject: Petition for Time-Limited Exemption from section 14 CFR Part 25.981(a)(3) for the Fuel Tank Ignition Prevention of the Bombardier Aerospace BD-500-1A10 and BD-500-1A11(C Series CS100 and C Series CS300 respectively) aircraft
models

FAA Project No.: TC4948NY-T

Dear Mr. Duven,

In accordance with 14 CFR Part 11, Bombardier Aerospace (BA) respectfully submits this petition for a time-limited exemption of the C Series aeroplane models BD-500-1A10 (CS100) and BD-500-1A11 (CS300) from full compliance with 14 CFR 25.981(a)(3) at amendment 131, as it is applicable to the AC fuel boost pump igni tion prevention. Please see the enclosed issue description for additional details.

If you have any questions or require any additional information please contact Glenn Baxter via the contact information listed below.

Best regards,

Manager, C Series Airworthiness Bombardier Aerospace glenn.jr.baxter@aero.bombardier.com

Enclosure U. S. Department of Transportation
ATTN: Jeff Duven Docket Management System 1200 New Jersey Avenue, SE Washington, D.C. 20590

Glenn Baxter

### Bombardier Airworthiness Coordination Sheet

Subject: BA letter AW-BD5/16/073, titled “Petition for Time-Limited Exemption from section 14 CFR Part 25.981(a)(3) for the Fuel Tank Ignition Prevention of the Bombardier Aerospace BD-500-1A10 and BD-500-1A11(C Series CS100 and C Series CS300 respectively) aircraft models”, dated 2016-
01-29.

Reference(s) : 1. Airworthiness – C Series Certification eRoom Action Item #4271

DISCIPLINE NAME APPROVAL DATE

Fuel DAD V. Furgiuele

Fuel DAD P. Gervais

Airworthiness Focal C. Groombridge

Airworthiness Manager G. Baxter

### EXEMPTION REQUEST FORM

Petition for Exemption
Bombardier Inc. Fuel Tank Ignition Prevention

Models BD-500-1A10/1A11 Relief from section 14 CFR Part 25.981(a)(3)

SUMMARY

Sections of the Regulation Affected :

14CFR §25.981(a)(3)

Description of Relief Sought :

Time-Limited Exemption of Bombardier Aerospace BD-500-1A10 and BD-500-1A11 Aircraft from the 14CFR § 25.981(a)(3) requirement as it relates to the Fuel Tank Ignition Prevention, no ignition source may be present at each point in the fuel tank.

Text of Requirement for which Exemption is Sought :

14 CFR §25.981(a)(3) "Highest Temperature Limit" (a) No ignition source may be present at each point in the fuel tank or fuel tank system where 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.

### EXEMPTION REQUEST FORM

Bombardier Aerospace (BA) respectfully requests a time-limited exemption to Federal Aviation Regulation (FAR) Part 25.981(a)(3) of CFR Title 14, as it is related to the fuel AC boost pump design on the BD-500-1A10 and BD-500-1A11 (C Series CS100 and C Series CS300, respectively). In particular where the regulation states to cater for “ aging, wear, corrosion, and likely damage”.

The exemption is requested for a 3 year period after F AA type validation. Due to the impracticality of quick redesign to include a ground fault interrupter (GFI) or a fast acting arc fault protection, BA believes temporary relief from 14CFR 25.981(a)(3) relative to the fuel boost pump is appropriate. The design change will be introduced into production. Furthermore, BA understands precedent exists with the FAA for this relief, most recently with FAA Exemption number 11321.

Justification

BA has described the details in FAA Issue Paper P-32 where the AC boost pump design is claimed to meet dual fault tolerant methodology. Full compliance with 14 CFR 25.981(a)(3) will require introduction of a GFI or a fast acting arc fault circuit protection device. BA strongly believes that the AC boost pump design as outlined in IP P-32 stage III BA response, fully demonstrates that the design is robust with many redundant ignition protecti on features to prohibit any single failure, from each single failure in combination with each latent failure condition, and from all combinations of failures to not be a threat to fuel tank ignition. At this time BA is assessing and evaluating potential design solutions to incorporate either a GFI or a fast acting arc fault circuit protection device into the AC boost pump external electrical wiring of t he BD-500-1A10 and BD-500-1A11 in order to fully comply to 14 CFR 25.981(a)(3).

Issue of Public Interest

Since the incorporation of this additional feature is in development, this prevents BA from certifying the C Series CS100 and CS300 design within a timely and competitive schedule, putting the product at an unfair disadvantage. This will in due course directly impact potential US customers as well as BA US suppliers whic h are heavily involved in the development of the C Series aircraft.

BA’s current design has been certified by Transport Canada during the baseline certification program for the C Series CS100 aircraft. The identified FAA concerns require significant aircraft utilization and/or aging to potentially develop into a non-compliant condition. The AC boost pump is not used continuously and therefore the timeframe proposed for this exemption is not sufficient for the affected airplanes to accumulate the flight hours or cycles required for the components to exhibit these aging effects.

### EXEMPTION REQUEST FORM

Effect of the Exemption on Safety

While issuing an exemption implies a lower standard of safety, BA believes that the pump as designed is more robust and better suited to preventing ignition sources than those currently installed on thousands of aircrafts that did not require to meet the requirements of 14 CFR 25.981(a)(3) at Amendment 25-125. Therefore, BA believes there will be no negative impact on the current level of safety. Furthermore, the robust design of the CS100 and CS300 fuel boost pumps in comparison to that of in-service aircraft not meeting the standards of 14 CFR 25.981(a)(3) at Amendment 25-125 will result in an increase in safety. In addition, the time limited nature of this exemption will ensure that th e number of airplanes delivered is negligible to the overall fleet risk.

Waiver of Notice and Public Procedure

BA respectfully requests that action on this petition should not be delayed by publication and comment procedures. BA believes that the proposed design change, required for fuel boost pump, justifies this request.

Conclusion

BA believes that the above arguments favor a time-limited exemption from 14 CFR 25.981(a)(3) regarding fuel tank ignition for the C Series 100 and C Series 300 aircraft. Additionally, BA believes that any risk due to a fuel tank ignition is mitigated by the multiple safety features BA has incorporated (as defined in issue paper P-32). The AC boost pump failure condition on the CS100 and CS300 will not exceed that of comparable existing transport category airplanes and that an exemption is in the public interest. BA requests that the privileges of this exemption would apply outside the United States due to the transoceanic capability of the CS100 and CS300 aircraft and the character of mission for many of our operators.