Regulatory Brief -- FAA issues AD on Cessna 172 map light and fuel lines

Regulatory Brief

FAA issues AD on Cessna 172 map light and fuel lines

The issue:

On November 15, 2001, the FAA issued a final rule AD that supersedes previously issued AD 80-04-08 and requires repetitive inspection of map light switches and fuel lines installed on certain Cessna 172 airplanes. The AD requires a one-time inspection for presence and proper condition of the map light switch insulator. The AD, intended to prevent fuel leaks, electrical arcing, and potential in-flight fire, also requires repetitive inspection/replacement of the map light switch cover and replacement of chafed or otherwise damaged fuel lines.

The importance to our members:

The AD affects an estimated 7,750 U.S. registered airplanes. The FAA estimates that initial inspections will cost $60/per airplane (1 hr. labor @ $60). Replacement map light switch covers cost approximately $6 plus labor, and replacement fuel lines (if necessary) cost between $26 and $129 plus labor.

Significant provisions:

The FAA cites the possibility that "chafing between the map light switch and the fuel line could continue to develop over the life of the effected airplanes" as primary cause for airworthiness action.
A search of NTSB accident data revealed two reports (LAX99FA106 and CHI99LA188 attached below) of non-fatal accidents involving in-flight fires suspected to originate as a result of chafing between the fuel line and map light switch and subsequent fuel leakage/electrical arcing. In both cases maintenance work had recently been performed on the map lights installed in the accident airplanes. Mechanics in both cases reported that they had reviewed and complied with the provisions of AD 80-04-08. In either case the NTSB could neither confirm nor deny the existence of the map light switch cover (Nomex insulator) and .50 inch minimum clearance between the fuel line and map light switch required by AD 80-04-08.
In one of the accident reports, the NTSB indicates that service difficulty reports highlight three instances where fires originated in the left forward doorpost as a result of electrical arcing between the fuel line and the map light switch. AOPA's search of publicly available SDR data revealed only one such report. That report (a duplicate report of the events highlighted in NTSB accident report LAX99FA106) confirmed that fire damage precluded any positive determination regarding the presence of the map light switch cover required by AD 80-04-08.
Cessna and the FAA first addressed this problem in 1980 through their respective issuance of Single Engine Service Letters SE80-3, SE80-3A, SE80-3 Supplement #1 and AD 80-04-08 (all attached below).
The AD affects Cessna 172N, 172P, 172RG, F172N, F172P, FR172J, FR172K, and R172K airplanes by serial number as listed in AD 2001-23-03 (attached below).
The AD requires a one-time inspection within the next 100 hours Time In Service (TIS) or within 12 calendar months for the presence and proper condition of the map light switch insulator. The AD also requires repetitive inspection/replacement of the map light switch cover and replacement of chafed or otherwise damaged fuel lines.
The inspections and parts replacements required by the AD must be accomplished in accordance with Cessna Service Bulletin SEB00-1, dated January 17, 2000 (attached below).
The FAA estimates that the cost of each repetitive inspection would be approximately $60 and estimated the cost of any necessary replacement parts to range from as little as $6 if only a map light switch cover is required to as much as $135 (depending on aircraft model) if a replacement fuel line must be installed. The FAA failed to include any estimation of the time/cost of labor necessary to complete any parts installations required by the proposed AD.

AOPA position:

AOPA agrees that, in this particular situation, the potential for chafing between the map light switch and the fuel line, subsequent fuel leakage and/or electrical arcing and possible in-flight fire warrants airworthiness concern. In-flight fire is undoubtedly a circumstance no pilot wishes to face. AOPA feels that this particular circumstance does warrant airworthiness action. Thus, AOPA agrees with FAA that affected aircraft should undergo inspection for installation and proper condition of the map light switch insulator, proper spacing between the fuel line and map light switch, and evidence of electrical arcing/damage to the fuel line.

Status:

On November 15, 2001, FAA published final rule AD 2001-23-03
On April 12, 2001, AOPA submitted comments to NPRM 2000-CE-26-AD
On February 12, 2001, the FAA extended the comment period to April 13, 2001.
On January 8, 2001, AOPA officially petitioned the FAA for a 120-day extension to the comment period of NPRM 2000-CE-26-AD.
On January 8, 2001, the FAA issued proposed AD 2000-CE-26-AD.