AFS-15-169-E

December 31, 2014

 Exemption No. 11129

 Regulatory Docket No. FAA-2014-0974

Mr. Rick DePriest

Director of Quality Assurance

TWC Aviation Inc.

1162 Aviation Ave.

San Jose, CA 95110

Dear Mr. DePriest:

This letter is to inform you that we have granted your request for exemption. It transmits our 

decision, explains its basis, and gives you the conditions and limitations of the exemption, 

including the date it ends.

The Basis for Our Decision

By letter, dated November 12, 2014, you petitioned the Federal Aviation Administration 

(FAA) on behalf of TWC Aviation, Inc. (TWC), for an exemption from § 135.152, Appendix 

F, parameter No. 5 (Normal Acceleration, Vertical) of Title 14 Code of Federal Regulations 

(14 CFR). This exemption, if granted, would allow one CL-600-2B16 (CL-604 Variant), 

N999VK, S/N 5499 airplane to continue to operate without complying with the required flight 

recorder data sampling rates of 14 CFR § 135.152, Appendix F. While the petition requests 

relief from Appendix F requirements, relief is actually required from the 14 CFR § 135.152, 

which requires compliance with Appendix F. The FAA has considered the petition as 

requesting relief from the 14 CFR § 135.152 requirements.

The FAA has determined that good cause exists for not publishing a summary of the petition 

in the Federal Register because the requested exemption would not set a precedent, and any 

delay in acting on this petition would be detrimental to TWC Aviation.

The FAA has issued a grant of exemption in circumstances similar in all material respects to 

those presented in your petition. In Grant of Exemption No. 11052 (copy enclosed), the FAA 

found that good cause exists to allow time for the airplane manufacturer to complete 

development of a modification to retrofit the subject aircraft with a redesigned data 
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concentrator unit (DCU) capable of providing the normal acceleration parameter information 

to the Digital Flight Data Recorder (DFDR) system to meet Appendix F requirements, and for 

the operators to modify their aircraft accordingly. The FAA does not agree with any assertion 

that flight recorder systems are not safety equipment simply because they do not affect the 

operation of a given flight. Flight recorder data are often the only evidence of airplane 

problems available to investigators following aircraft accidents and incidents. However, 

because the subject airplanes will still be recording flight data and the limitations are known, 

the FAA agrees that a limited time to complete the upgrades is appropriate.

The FAA finds that since the problem identified in this petition is a system design issue over 

which CL604 operators have no control or ability to fix, and that since the deficiency would 

be known to accident investigators and can be compensated for in any necessary analysis, it is 

in the public interest to allow continued operation of a limited number of airplanes until the 

modifications can be incorporated.

The FAA has analyzed the petitioner’s request to operate outside the United States using this 

exemption to examine any effect on U.S. obligations under international agreements. The 

FAA finds that even with the exemption, the DFDR system installation on the subject 

airplanes meets or exceeds the recorder requirements of both Annex 6 of the International 

Civil Aviation Organization and the regulations of the European Aviation Safety Agency. 

Accordingly, the petitioner is permitted to operate the listed airplane outside of the United 

States under the conditions and limitations listed in this exemption.

Having reviewed your reasons for requesting an exemption, I find that—

 they are similar in all material respects to relief previously requested in the enclosed Grant 

of Exemption No. 11052;

 the reasons stated by the FAA for granting the enclosed Grant of Exemption No. 11052

also apply to the situation you present; and

 for the reasons stated in Grant of Exemption No. 11052, a grant of exemption is in the 

public interest.

Our Decision

Under the authority contained in 49 U.S.C. §§ 106(f), 40113 and 44701, which the FAA 

Administrator has delegated to me, I hereby grant TWC Aviation an exemption from 14 CFR 

§ 135.152 to the extent necessary to allow the listed airplane to operate without complying 

with the Normal Acceleration (Vertical) data recording rate requirement listed in Appendix F 

to 14 CFR part 135, subject to the conditions and limitations listed herein.

Conditions and Limitations 
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1. This exemption applies only to the following airplanes while it remains on the part 135 

operations specifications of TWC: CL-600-2B16, N999VK, S/N: 5499.

2. This exemption allows for the continued operation of the affected airplane with a DFDR 

that receives data from the source sensor for the Normal Acceleration (Vertical) parameter 

at a rate of 0.2 rather than the 0.125 as required by 14 CFR Appendix F to part 135. No 

other relief from any other parameter requirement or other flight data recorder provision 

of 14 CFR part 135 is granted by this exemption.

3. TWC must establish a firm schedule for accomplishment of the modifications required to 

bring the subject airplane into compliance and submit the schedule to its oversight office. 

The schedule must include the following milestones:

a. Bombardier service bulletin issued no later than September 30, 2015;

b. TWC’s plan for incorporation of the service bulletin on the subject airplane, to be 

submitted to its Principal Avionics Inspector or other cognizant oversight office no 

later than December 1, 2015. The plan must include a modification date within the 

term of this exemption for the airplane listed in condition 1 above;

c. Starting December 1, 2015, TWC must provide monthly status reports to its 

oversight office outlining the completion of the aircraft modifications necessary to 

bring its aircraft into compliance with the requirements of 14 CFR § 135.152.

4. Noncompliance with any term of these conditions and limitations terminates this 

exemption without further action by the FAA. 

5. Use of this exemption is limited to TWC while the subject airplane remains on its part 135 

operations specifications. This exemption may not be transferred to any subsequent 

operator of the affected airplane. Subsequent operators of the affected airplane must 

apply for and be granted an exemption in writing before such airplane may be operated if 

the airplane has not been modified to comply with 14 CFR § 135.152. 

6. A copy of this exemption must be retained with the operator's DFDR correlation 

documentation as specified in the applicable provisions of 14 CFR § 135.152 until the

airplane identified in this exemption has been modified. 

7. In the event of an accident or incident after which the DFDR recording media must be 

removed and retained subject to 14 CFR § 135.152(e), the operator must provide a copy of 

this exemption together with the recording media when submitted. 

8. This exemption may be used for operations outside the United States.
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This exemption terminates on the sooner of the completion of the modification described in 

this exemption that brings the airplane into compliance with 14 CFR § 135.152, or on January

31, 2017, unless sooner superseded, rescinded or terminated.

Sincerely,

/s/

John S. Duncan

Director, Flight Standards Service

 

Enclosure 

Exemption No. 11052