AFS-14-074-E

Exemption No. 10969

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

 

In the matter of the petition of 

 

OPERATORS OF CERTAIN Regulatory Docket No. FAA- 2013-1048

BOMBARDIER AEROSPACE

DHC-8-400 SERIES AIRPLANES

 

for an exemption from § 121.346(d)(3)(i)

and 121.346(d)(4) of Title 14, Code of 

Federal Regulations

 

 

GRANT OF EXEMPTION

By letter dated December 5, 2013, James Boothe, Director of Quality Assurance, Republic 

Airlines, 8909 Purdue Road, Suite 300, Indianapolis, Indiana, 46268 (Republic), petitioned 

the Federal Aviation Administration (FAA) for exemption from §§ 121.346(d)(3)(i) and 

121.346(d)(4) of Title 14, Code of Federal Regulations (14 CFR). The proposed exemption, 

if granted, would allow the operator to continue operation of its 34 Bombardier Aerospace 

DHC-8-400 airplanes after April 21, 2014, without complying with the prohibition on the 

filtering of flight recorder data of § 121.346.

On December 10, 2014 [sic], Carl Allen, Horizon Air, 8070 N.E. Airtrans Way, Portland, OR, 

97218 (Horizon), petitioned for exemption from the same regulations for Horizon’s 51 

Bombardier Aerospace DHC-8-400 airplanes. 

The petitioners request relief from the following regulations:

Section 121.346(d)(3)(i) requires in pertinent part that airplanes found to be filtering any 

parameter listed in paragraph (c) of that section must remove the filtering no later than 

April 21, 2014.
2

Section 121.346(d)(4) requires in pertinent part that after April 21, 2014, no aircraft flight data 

recording system may filter any parameter listed in paragraph (c) of that section that does not 

meet the requirements of Appendix B or M of part 121, unless the certificate holder possesses 

test and analysis procedures and the test results that have been approved by the FAA, and that 

the correlation documents are maintained as required by part 121. 

The petitioners support their requests with the following information:

Both petitioners submitted identical letters from the aircraft manufacturer, Bombardier 

Aerospace, supporting the operators’ requests for a three-month exemption from the filtering 

prohibition in part 121. The letter explains the configuration of the DHC-8-400 flight data 

recorder system, and notes that “to accommodate additional parameters required by the FAA 

in 14 CFR Part 121 in 2010, a Flight Data Recorder Signal Conditioning Unit (FSCU p/n 

1152862-X) was designed and manufactured by Honeywell [International, Inc. (Honeywell)] 

to install on the DHC-8 Series 400 aircraft.”

The letter then describes the changes to the regulations made by the FAA in 2010 to restrict 

data filtering, including the addition of Section 121.346. Bombardier and Honeywell did an 

analysis of the flight recorder parameters affected by the rule and determined that the DHC-8 

Series 400 aircraft were not in compliance. Bombardier informed the affected U.S. operators 

of its aircraft of the situation in September 2011. 

Between January and July 2012, “several significant technical and business issues” became 

apparent, including whether the filtering could be removed without additional hardware 

modification, the fact that other regulatory changes had consumed much of the processing 

time for the manufacturers, and whether removal of the filtering software might introduce an 

unacceptable level of sensor noise to be recorded, requiring additional software logic. 

The letter goes on to detail Bombardier and Honeywell’s efforts to resolve the issues 

throughout 2012 and 2013. The letter concludes that the updated FSCU would not be 

available for installation on in-service airplanes until February 17, 2014. The replacement and 

return to service is expected to take 6 hours per airplane, with an intent to perform one 

upgrade per night at each of the petitioner’s facilities. Bombardier also warned that older units 

may require additional upgrades and require rework at Honeywell, delaying the planned 

upgrade schedule. Bombardier asked that the two affected operators be granted a three month 

extension from the April 21, 2014, compliance date.

Petitioner Republic Airlines noted that without an exemption, it would have to ground its 

aircraft with serious disruption to its business and customers. It also notes that the regulatory 

changes regarding filtering are meant to improve accident investigation, but do not have a 

direct impact on the safety of a given flight. 
3

Petitioner Horizon Air included with its petition a memo from Honeywell detailing the same 

issues as described in the Bombardier letter to its customers, and which reflects a proposed 

installation completion date of July 2014. Horizon indicated that it too would be forced to 

remove aircraft from service if the exemption is not granted, causing a cancellation of flights 

and delays of passengers. For these reasons, Horizon states that an exemption would be in the 

public interest. Similar to Republic, Horizon states that the flight recorder is an accident 

investigation tool that does not directly impact the safety of flight. 

A summary of the petition of Horizon Air, Docket No. FAA-2013-1048, was published in the 

Federal Register on January 21, 2014 (79 FR 3454). Comments on the petition were due 

February 10, 2014. No comments were received. 

The FAA's analysis is as follows:

The FAA amended the regulations prohibiting flight data recording filtering in 2010, with four 

years for compliance. Materials submitted by the petitioners indicate that the manufacturer of 

their airplanes did the required analysis in 2011 and found that the DHC-8-400 series was 

filtering some flight data and began a program with the avionics equipment producer to 

upgrade the equipment to be compliant with part 121. While each operator remains 

responsible for the operation of its airplanes and the equipment installed on it, the FAA 

understands that these two operators have been significantly impacted by the delays of the two 

manufacturers in designing and certifying compliant equipment that are beyond the operators’ 

control.

The FAA finds that good cause exists to allow additional time to retrofit the subject aircraft 

with compliant equipment. The FAA reminds operators that flight recorder systems are 

considered safety equipment simply even if they do not affect the operation of a given flight. 

The petitioners note that flight recorders are investigational tools. Flight recorder data are 

often the only evidence of airplane problems available to investigators following aircraft 

accidents and incidents, and filtered data were shown to have significantly inhibited the 

investigation of the cause of a well-known aircraft accident, possibly delaying the corrective 

action that was necessitated. However, because the subject airplanes will still be recording 

flight data and the limitations of its systems are known, the FAA agrees that a limited time to 

complete the upgrades is appropriate and that the public interest will be served by allowing 

continued operation of the operator’s affected airplanes. 

This grant of exemption includes a list of the identified airplanes that may take advantage of 

this exemption relief. Relief is limited to those airplanes identified in the list. Operators of 

other airplanes of the models noted may petition the FAA to be included in the relief, but must 

have written FAA approval before such relief may be exercised. All of the airplanes included 

on this list are subject to all of the conditions and limitations included in this petition even if 

they differ from a petitioner’s initial request. Operators that fail to comply with all of the 

listed conditions and limitations are prohibited from continued use of their airplanes after 

April 21, 2014, until the aircraft are fully compliant with the requirements of part 121. 
4

Since there are only two operators of the affected aircraft, both must be aware that exchanges 

of or loan of affected airplanes does not cause the exemption to transfer. Such operations are 

restricted to the procedure listed in item 5. of the conditions and limitations contained herein. 

All modifications to airplanes necessary to comply with the flight recorder filtering 

regulations of 14 CFR Part 135 must be completed as soon as possible, and no later than 

October 21, 2014. Once modifications are completed on an airplane, the relief provided by 

this exemption terminates. No extensions of this exemption will be considered. 

The FAA’s Decision

In consideration of the foregoing, I find that a grant of exemption is in the public interest. 

Therefore, pursuant to the authority contained in 49 U.S.C. §§ 106(f), 40113 and 44701, 

delegated to me by the Administrator, the petition for an exemption from 14 CFR 

§§ 121.346(d)(3)(i) and 121.346(d)(4) is granted to the extent necessary to allow the operators 

of the Bombardier DHC-8 Series 400 airplanes described in item 9 below to temporarily 

operate these airplanes subject to the conditions and limitations listed herein.

Conditions and Limitations

1. This exemption applies only to the airplanes listed in the table included in item 9 below. 

2. In order to continue the operation of any airplane identified in this exemption, each operator 

of an affected airplane must, within 10 days of the issuance of this exemption but not later 

than April 18th, 2014, submit a letter to its principal inspector requesting to use this exemption 

including:

a. A list of the airplanes that the operator has determined are subject of this 

exemption, identified by model, serial and current registration numbers; and 

b. Acknowledgement of the conditions and limitations listed in this exemption as the 

basis for continued operation of the airplane until it is modified.

3. The letter required in item 2 must also be filed concurrently in Regulatory Docket 

No. FAA-2013-1048 by the operator requesting the relief. 

4. This exemption allows for the continued operation of affected aircraft with a DFDR that 

records filtered flight data for parameters 12, 13, 14 and 88 as described in 14 CFR

§ 121.344(a), as applicable. No other relief from any other parameter or other flight recorder 

provision of Part 121 is granted by this exemption. 
5

5. Use of this exemption is not transferable to a subsequent operator of an affected airplane 

without the prior written approval of the FAA. Use by a subsequent operator is subject to 

written request and FAA approval before the airplane may be operated. 

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

documentation as specified in 14 CFR § 121.346 as applicable until the airplane identified in 

this exemption has been modified pursuant to this exemption. 

7. In the event of an accident or incident after which the DFDR data must be sent to the FAA 

or the National Transportation Safety Board, the operator must provide a copy of this 

exemption. 

8. Within 10 days of submission of the letter required in Condition No. 2 above, the operator 

must provide to its principal avionics inspector a schedule for the completion of the 

modifications required to bring each airplane into compliance with the applicable regulation. 

Such schedule may not extend beyond the date of termination of this exemption. Monthly 

updates of the modification schedule must be provided by each operator to its principal 

avionics inspector until the modifications are complete and each airplane complies with

Title 14 CFR § 121.346.

9. Table of Affected Aircraft

DHC-8-402 4030

DHC-8-402 4031

DHC-8-402 4032

DHC-8-402 4036

DHC-8-402 4037

DHC-8-402 4046

DHC-8-402 4047

DHC-8-402 4048

DHC-8-402 4049

DHC-8-402 4050

DHC-8-402 4051

DHC-8-402 4053

DHC-8-402 4055

DHC-8-402 4059

DHC-8-402 4060

DHC-8-402 4061

DHC-8-402 4067

DHC-8-402 4081

DHC-8-402 4083

DHC-8-402 4086
6

DHC-8-402 4129

DHC-8-402 4143

DHC-8-402 4145

DHC-8-402 4147

DHC-8-402 4149

DHC-8-402 4150

DHC-8-402 4153

DHC-8-402 4154

DHC-8-402 4156

DHC-8-402 4160

DHC-8-402 4161

DHC-8-402 4163

DHC-8-402 4164

DHC-8-402 4166

DHC-8-402 4168

DHC-8-402 4181

DHC-8-402 4182

DHC-8-402 4186

DHC-8-402 4187

DHC-8-402 4188

DHC-8-402 4190

DHC-8-402 4191

DHC-8-402 4195

DHC-8-402 4196

DHC-8-402 4199

DHC-8-402 4202

DHC-8-402 4203

DHC-8-402 4204

DHC-8-402 4208

DHC-8-402 4209

DHC-8-402 4210

DHC-8-402 4213

DHC-8-402 4214

DHC-8-402 4227

DHC-8-402 4232

DHC-8-402 4235

DHC-8-402 4236

DHC-8-402 4240

DHC-8-402 4243

DHC-8-402 4246

DHC-8-402 4323
7

DHC-8-402 4328

DHC-8-402 4332

DHC-8-402 4333

DHC-8-402 4336

DHC-8-402 4338

DHC-8-402 4339

DHC-8-402 4340

DHC-8-402 4341

DHC-8-402 4342

DHC-8-402 4345

DHC-8-402 4346

DHC-8-402 4347

DHC-8-402 4348

DHC-8-402 4351

DHC-8-402 4352

DHC-8-402 4353

DHC-8-402 4354

DHC-8-402 4355

DHC-8-402 4356

DHC-8-402 4358

DHC-8-402 4363

DHC-8-402 4364

DHC-8-402 4380

DHC-8-402 4409

DHC-8-402 4410

DHC-8-402 4452

DHC-8-402 4457

DHC-8-402 4459

This exemption terminates on the sooner of the installation of the software update correcting 

the problem as stated above, or October 21, 2014, unless sooner superseded or rescinded.

Issued in Washington, DC, on April 1, 2014.

/s/

John S. Duncan

Director, Flight Standards Service .