Petition for Rulemaking

Submitted by:

James Sparks

Richardson Aviation

3800 Lincoln Avenue

Fort worth, Texas 76106

Telephone: 817 339 7633

Email: jsparks@richav.com

Action Requested:

Improve the clarity of statements by revising language in FAR 91.411 and FAR 

43 Appendix E related to persons authorized to return an aircraft to service after 

maintenance other than transponder or altimeter certification. 

The concern deals with a compromise of the data link between an air data unit and

a transponder. 

Paragraph b, line (3) states “A certificated mechanic with an airframe rating (static pressure 

system tests and inspections only).” as one of the options for return to service. The 

caveat implies the certified mechanic is not capable of insuring the integrity of 

the data link. Statements made in paragraph (a) of Part 43 Appendix E do fall

in line with the authority granted an Airframe Mechanic under Part 43.3 which

implies that is the qualification for return to service of the system in paragraph

(c) of Appendix E.

Aircraft produced during the last decade use integrated systems relying on digital

technology to validate the communication between altimetry and surveillance

systems and can be verified through the use of Built In Test Equipment (BITE). 

Enhanced diagnostics need to be included as part of return to service criteria.

Airframe manufacturers often include tests for return to service in their approved

maintenance programs for Part 25 aircraft. Technicians should be directed to these

approved methods as an alternate means of compliance when applicable to

fulfilling requirements of Part 43 Appendix E paragraph (c).

Proposed language:

Please review attached Part 91.411 and Part 43 Appendix E with proposed 

changes noted in blue italic and underlined.

Proposed benefit to public interest:

The current wording used in Part 91.411 and Part 43 appendix E do not clearly

define the role and authorizations for those involved in the different tests and 

inspections listed. The current rules may be interpreted that after maintenance

occurring within the two year certification period that it is required to have an 

appropriately rated repairman conduct a transponder test while a mechanic with 

an airframe rating (or an appropriately rated repair facility) conduct the static 

system test.

By clarifying that the two year component and system certification has different

requirements than return to service after maintenance will insure the most
qualified persons will be conducting the testing while reducing the perceived need

to have a repairman test the transponder and a mechanic validate the static system.

Using the onboard dedicated maintenance diagnostic equipment on aircraft with

integrated avionics will reduce the burden of redundant testing.

Support for the proposed action:

Clarification of qualification for transponder and integrated system testing has 

long been subject to interpretation. Advisory Circular AC43.6b was produced to 

provide guidance but is as ambiguous as the regulations. This situation does need 

to be put in perspective so that it is understood; certifying altitude indicating and 

reporting equipment for the 24 month term does require a specific knowledge 

level skill set and perhaps test equipment not possessed by most Airframe 

Mechanics. A Part 43.3 rated Airframe Mechanic does not have an approval for 

instrument repair or certifying the full Part 43 Appendix E or F compliance. The 

Mechanic is authorized to perform a check to verify proper altitude reporting 

allowing return of the aircraft to IFR service.

A repairman on the other hand is granted the authority to certify various 

instruments as meeting the criteria in Part 411 and 413 in accordance with Part 43 

Appendix E and F but may not have the authority to inspect and certify the 

aircraft static system(s).

An appropriately rated Airframe Mechanic does currently have the authority to 

perform the system tests necessary for verifying proper integration of the 

altimeter and transponder and should be provided clear and undisputable guidance 

on how to approve and document the work performed.