10/09/2014

Douglas R. Wolfe

Quality Manager

Flight Inspection Services

6500 S. MacArthur Blvd.

Oklahoma City, Ok 73169

AJW-347

douglas.r.wolfe@faa.gov

US Department of Transportation

1200 New Jersey Ave. SE

West Building Ground Floor, Room W12-140

Washington, DC 20590

Submitted via: www.regulations.gov

Subject: Request for Temporary Exemption to CFR 135.152 Parameter 5 "Normal 

Acceleration"

Dear Sir or Madam,

It was brought to the attention of Flight Inspection Services (FIS) Air Carrier 

Certificate Number RU3A249N by Bombardier Aerospace (BA) that certain Digital Flight

Data Recorder (DFDR) systems certified and installed by BA on certain aircraft are not 

recording a specific parameter listed in 14 CFR 135 Appendix F - "Airplane Flight

Recorder Specification" to the full stated specifications listed for this specified

parameter.

Therefore, in anticipation of suitable rectification by BA, Flight Inspection Services is 

requesting exemption from the requirements of 14 CFR 135 Appendix F - "Airplane 

Flight Recorder Specification", specifically "5. Normal Acceleration (Vertical)" only. This 

request applies to Bombardier Challenger CL-600-2B16 (CL-604 Variant) manufactured 

after August 18, 2000 and with a DFDR system installed per Bombardier Aerospace 

SB604-31-010 operating under 14 CFR 135 by Flight Inspection Services 

domestically and abroad, currently N88 is the affected aircraft.
- 2 - October 14, 2014

PETITION FOR EXEMPTION

Specific Section and Extent of Relief Requested

In accordance with 14 CFR 11 Flight Inspection Services, requests an exemption 

from the "5. Normal Acceleration (Vertical)" parameter requirements in Appendix F of 14 

CFR 135.152 to permit sampling 5 times (0.2 seconds per sampling interval) per second 

until the Data Concentrator Unit (DCU), a subsystem of the affected DFDR system, is 

updated to provide 8 times per second (0.125 seconds per sampling interval) per 

second.

An exemption will have no adverse impact on the safe operation of the aircraft.

The DFDR and its recorded parameters are not required for the safe operation of the 

aircraft. The DFDR's primary purpose is to support investigations in case of accidents.

The affected Normal Acceleration parameter is provided through the DCU. Flight 

Inspection Services CL604 variant aircraft has/have two DCUs. Except for the 

affected Normal Acceleration sampling rate, all data is being collected as required by 14 

CFR 135 Appendix F (e.g. range -3g to +6g, resolution 0.004). The effect is that the 

normal acceleration parameter can be correlated to the appropriate recording rate, as 

described and illustrated below, with no substantive loss of information.

Given that the information can be effectively correlated with no substantive degradation 

in information, we respectfully submit that this compliance issue does not affect the safe 
- 3 - October 14, 2014

operation of the aircraft or hinder potential investigations requiring the DFDR data.

Bombardier Aerospace has committed to developing an in-service solution that involves 

a re-design of the DCU on or before September 20151. Additionally Bombardier 

Aerospace has indicated that a subsequent fleet retrofit period to account for parts 

availability and all affected operators downtime requirements, for a complete retrofit 

within two (2) years of the grant of the exemption. Flight Inspection Services is 

committed to working with Bombardier Aerospace to effect the final rectification to this 

issue concerning our affected aircraft as soon as practical.

In many cases our affected aircraft are outside the United States for an extended 

period. The public benefit and equivalent level of safety addressed below supporting 

this exemption request have equal applicability to Flight Inspection Services

international flights.

The exemption is in the public interest

The problem identified above was found by the aircraft manufacturer (Bombardier), and 

is a systems design problem which CL604 operators have no way to correct at this time. 

Granting this time limited exemption would be in the public interest because it would 

allow U.S. Part 135 operators the ability to continue to provide the unique services that 

support US public, business and industrial leaders while the aircraft manufacturer 

develops and certifies, and the affected CL604 operators incorporate, the modifications 

necessary to bring these aircraft into compliance. This request is substantially similar to 

the Exemption No. 11052 granted to Jet Solutions. L.L.C. in FAA Docket No. 2014-0542 

on September 11, 2014.

Conditions and Implementation

Flight Inspection Services requests that the FAA to allow continued operation of our

aircraft subject to the conditions specified below:

1. This exemption is valid until the incorporation of the modification correcting the 

deficiency described herein or 24 months from the date of this exemption, 

whichever occurs first, unless previously superseded, rescinded or terminated by 

action of Flight Inspection Services

2. Copies of this exemption to be retained by Flight Inspection Services, and the

requirement that a copy be provided to the NTSB and FAA in connection with any 

accident or incident where DFDR data is requested or required to be provided; and
- 4 - October 14, 2014

3. Within 90 days of receipt of the Bombardier Aerospace Service Bulletin that 

rectifies the Normal Acceleration parameter issue; Flight Inspection Services

must provide a schedule to its FAA CHDO principal avionics inspector (PAl), 

and/or persons designated by the FAA for completion of the new installation within 

the time period of this requested exemption.

Federal Register Summary and Publication

Flight Inspection Services, Air Carrier Certificate number RU3A249N, is requesting

exemption from the requirements of 14 CFR Appendix F of 135.152 to permit the 

sampling rate of 5 times (0.2 seconds per sampling interval) per second2until 

Bombardier Aerospace issues a Service Bulletin that corrects the issue, and in 

accordance with the conditions specified in this exemption request.

This applies to all its CL604 aircraft used in operations under 14 CFR 135. Flight 

Inspection Services also requests to utilize the exemption outside the United States. It 

is Flight Inspection Services position that safety would not be jeopardized by issuance 

of this exemption as the DFDR is used solely as a recording device in accidents and 

incidents and the affected parameter will still provide useful data in such cases. This 

exemption will benefit the public by allowing U.S. Part 135 operators the ability to 

continue to provide the unique services that support US public, business and industrial 

leaders while the aircraft manufacturer develops and certifies, and the affected CL604 

operators incorporate, the modifications necessary to bring these aircraft into 

compliance.

Due to the immediate and future impact and because this request does not establish 

new agency precedent as it is consistent with the scope of Exemption 11052, Flight 

Inspection Services requests a waiver to the 120 day filing requirements and the 

publishing of a summary of the petition in the Federal Register.

If there are any questions, please do not hesitate to contact this office at any time.

1 As indicated by Bombardier and based on the following: "The development schedule takes into account 

current Bombardier and its suppliers resource capacities. The FAA is involved in some of the joint projects, 

including but not limited to the Challenger Avionics upgrade as well as Steep Approach certification and 

operational approval."