AFS-1483-E

Exemption No. 15243

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

 

In the matter of the petition of 

 

THE BOEING COMPANY Regulatory Docket No. FAA-2014-0702

 

for an exemption from §121.344(e)(1) 

and (f)(1)of Title 14, Code of 

Federal Regulations 

 

DENIAL OF EXEMPTION

By letter dated September 2, 2014, Mr. Tim Hendrix petitioned the Federal Aviation 

Administration (FAA) on behalf of The Boeing Company (Boeing) for an exemption from 

§§ 121.344(e)(1) and (f)(1) of Title 14, Code of Federal Regulations (14 CFR) to the extent 

necessary to allow U.S. operators of certain Boeing 717-200 aircraft to operate those aircraft 

without complying with the recording rate required for parameter 46 (§121.344(a)(46), Nav 1 

and 2 selected frequency). The recording rate for that parameter is specified in Appendix M

to part 121. 

The petitioner requests relief from the following regulations

Section 121.344(e)(1) prescribes, in pertinent part, that for all turbine-engine-powered 

transport category airplanes that are manufactured after August 18, 2000, the parameters 

listed in paragraphs (a)(1) through (57) of this section must be recorded within the ranges, 

accuracies, resolutions, and recording intervals specified in Appendix M of part 121.

Section 121.344(f)(1) prescribes, in pertinent part, that for all turbine-engine-powered

transport category airplanes manufactured after August 19, 2002, the parameters listed in 

paragraphs (a)(1) through (a)(88) of this section must be recorded within the ranges, 

accuracies, resolutions, and recording intervals specified in Appendix M to part 121.
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The petitioner supports its request with the following information:

Boeing states that one 717-200 operator reported to Boeing that a portion of the data required 

by 14 CFR § 121.344(a)(46) was not being recorded correctly by the Digital Flight Data 

Recorder (DFDR). As part of parameter 46, the 717-200 airplane's DFDR is required to 

record Automatic Direction Finder (if equipped), Very High Frequency Omni-Directional 

Range (VOR), and Instrument Landing System (ILS) frequency selected. The ILS frequency 

selected is not being properly recorded.

The 717 has two interchangeable Versatile Integrated Avionics (VIA) units that supply

specified central computer functions for the airplane. The cause of the issue was identified by 

Boeing as a software coding error in the VIA which is sending unreadable data for ILS 

frequency selection from the Digital Flight Data Acquisition Unit (DFDAU) to the DFDR.

Boeing states there are 84 U.S.-registered 717 airplanes subject to the applicable regulations.

Boeing provided an attachment to its petition including a flow chart outlining the time 

required for rectification of the VIA unit software anomaly. Boeing estimates a total of 60 

months will be required, stating that:

“The 717 has been out of production for 8 years, therefore, the OEM VIA software 

supplier has no sustaining contract with Boeing. Changes to the existing VIA software 

require significant work scope and costs due to the criticality of this function on flight 

operations.”

Further, Boeing states:

“Boeing has accumulated a significant number of VIA software changes that are 

committed to the FAA for corrective action. In addition, 717 operators have requested 

new features which were planned to be included in this future change activity.” 

Boeing cites the time required for certification of software revisions as a key factor in the 

modification schedule. Finally, Boeing states that some revisions to the software will require 

flight testing prior to certification. This will necessitate Boeing negotiating use of a 717-200 

with one of the airplane’s operators.

Boeing lists the following as mitigating factors to the inability of the subject airplanes to 

record ILS frequency selected:

 The 717 DFDR records Localizer (Parameter 27) and Glide Slope (Parameter 28) 

tracking data. This, combined with radar tracking data and/or other physical data, will 

provide post event investigative evidence of proper/improper ILS frequency selection.
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 The 717 has auto tuning of navigation frequencies from a database for activated flight 

plans within the flight management system, thus reducing manual tuning entry errors 

of ILS frequency.

 The 717 has auto decoding of tuned navigation station Morse code identifiers which is 

displayed to the pilots.

 No accidents/incidents where ILS frequency tuning errors were causal or contributed

to the event in the past 15 years, including all airplane types and models in part121 

operations. (NTSB data)

 The affected U.S.-registered 717 fleet is relatively small at eighty-four (84) airplanes 

or approximately one percent (1 %) of the total airplanes operating under part121.

Boeing states that a similar grant of exemption has been issued by the FAA to another

transport category aircraft manufacturer for an unreadable parameter required under 14 CFR

§ 121.344, for the purpose of enabling continued operation of airplanes for a limited time until 

needed airplane modifications could be accomplished.

Boeing states there is no direct impact on safety of daily flight operations stemming from the 

unreadable ILS selected frequency DFDR parameter.

Boeing claims that a grant of its petition is in the public interest petition because it would 

allow continued operation in revenue service of 84 U.S.-registered model 717 airplanes, in 

service with three U.S. operators. It also claims that a grant of exemption “...would prevent 

severe economic impact to scheduled commercial operators with 717 airplanes if operations 

were required to cease until this issue is corrected on each airplane.”

The FAA’s analysis is as follows:

The FAA has determined that good cause exists for waiving the requirement for Federal 

Register publication because the exemption, if granted, would not set a precedent, and any 

delay in acting on this petition would be detrimental to Boeing.

Boeing has requested this exemption on behalf of three U.S. part 121 operators of this aircraft. 

Boeing indicated that 14 CFR §25.1549, an airworthiness standard for transport category 

airplanes, “supports compliance to” the operating requirements of §121.344 and that Boeing 

is “responsible to provide the source parameters and/or signals to interface with a flight 

recorder,” adding that the unreadable source data stream “resides within the Boeing 717-200 

Type Design VIA.” 

The FAA notes that the only other exemption to 14 CFR part 121.344 granted in response to a 

petition from another transport category aircraft manufacturer is Exemption10611(a). Though 

that particular exemption was granted based on a petition from Airbus Industries, the 

exemption was granted to operators of the affected Airbus aircraft. Although similar in nature, 
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the present petition of Boeing and the referenced Airbus petition differ significantly in scope. 

Both manufacturers identified a problem meeting the recording requirements of a single 

parameter, and both showed that the required data could be sufficiently ascertained using 

extrapolation of other recorded data in the event the need arose. Each manufacturer stated 

that a service bulletin would be published that would correct the deficiency and bring the 

affected aircraft into compliance with applicable regulations. Such similarities are common to 

many flight recorder exemption requests, but there are significant differences between the 

subject petition and the Airbus grant referenced. 

Airbus identified 345 aircraft operated under part 121 by 13 U.S. operators, all of which were 

directly affected by the condition described in its petition. All 13 U.S. operators and all 345 

affected aircraft required exemption from certain part 121 rules in order to continue operation. 

Boeing, by contrast, has identified 84 airplanes of U.S. registry that are affected. In its 

petition, Boeing identified three U.S. operators of the affected airplanes, but that number has 

been reduced to two operators since the petition was filed by the merging of operators.

The Airbus format exemption placed a more significant burden on the principal inspectors of 

the affected operators, which was balanced by the FAA’s need to process and oversee 13 

exemptions affecting hundreds of daily flights and thousands of passengers. It was a decision 

by the FAA to use a different process based on the circumstances. It is not to be considered 

an option that a petitioner may request in every instance, especially when the number of 

aircraft and/or affected operators is relatively small.

Airbus demonstrated an ability to provide recorded data of the discrepant parameter, but at a 

rate insufficient to meet certain regulatory requirements. Through extrapolation, this 

information would still be useful to accident investigators. In its petition, Boeing presents 

mitigations that include other recorded parameters, but would not include the discrepant 

parameter at any rate or accuracy. While investigators would be able to see the localizer and 

glideslope indications being presented to the flight crew, via recorded data, they would not be 

able to determine, for example, whether the avionics were malfunctioning or if an incorrect 

ILS frequency had been entered by the flight crew.

In its petition, Boeing requested a 24 month exemption, but the flow chart presented as an 

attachment to the petition shows, essentially, that the time will be used to determine what 

work will be done, primarily by the vendor, Honeywell. Indeed, fully a year is scheduled to 

“Negotiate with Honeywell” (6 months), “Confirm Schedule with Honeywell” (3 months), 

and “Sign Agreement with Honeywell and Operators” (3 months). At the end of the initial 24 

months, Boeing has scheduled processing of another petition for exemption of indeterminate 

length during which the actual software modifications will be developed and implemented. In 

total, Boeing estimates 60 months are required to develop and implement software revisions 

to bring the affected aircraft into compliance with regulations. The FAA finds this schedule 

unacceptable. 
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In its petition, Boeing mentions that other revisions to the VIA software will be accomplished 

concurrent with the revisions needed to bring the aircraft into compliance with the applicable 

flight recorder regulations. The FAA recognizes that there are economic benefits of

accomplishing multiple modifications concurrently, but that Boeing has not justified why it is 

in the public interest to allow its aircraft to remain out of compliance with §121.344 while 

other changes not affecting compliance are completed. 

While we appreciate the effort of Boeing to notify the FAA of a discovered noncompliance 

and to begin seeking relief for its operators, we do not find the circumstances warrant relief in 

the form requested. We suggest that Boeing notify the operators of the affected aircraft of the 

flight recordation deficiency and lend necessary technical support (as detailed in its petition) 

to those U.S. operators that apply for exemptions for affected airplanes that are listed on their 

operations specifications. The FAA does not grant exemptions to aircraft of foreign registry, 

nor is operation outside the United States automatically granted in any operational exemption. 

The FAA’s Decision:

In consideration of the foregoing, I find that a grant of exemption would not be 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, I deny the petition of The Boeing Company

for an exemption from 14 CFR § 121.344(e)(1) and (f)(1). 

Issued in Washington, D.C., on March 7, 2016.

/s/

John S. Duncan

Director, Flight Standards Service