Regulatory Brief -- FAA issues AD mandating inspection of Cessna 172 RG main landing gear pivot assemblies; ignores industry input

Regulatory Brief

FAA issues AD mandating inspection of Cessna 172 RG main landing gear pivot assemblies; ignores industry input

The issue:

On March 28, 2001 the FAA issued AD 2001-06-06 mandating inspection of the main landing gear pivot assemblies on all Cessna 172 RGs on the US registry. The AD also mandates the installation of new bushings on the main landing gear pivot assembly shaft and replacement of any cracked pivot assemblies.

The importance to our members:

The AD affects approximately 766 airplanes on the US registry. Aircraft Type-Clubs and owners/operators of affected airplanes have expressed serious concerns regarding the necessity of the actions proposed by the AD. Most owners hold that inspections and parts replacements are unnecessary for the majority of the fleet, as most aircraft are not regularly engaged in operations that result in abnormally high landing loads. Further, aircraft type-clubs familiar with the Cessna 172RG point out that the Cessna service bulletin provides other means to detect cracked main landing gear pivot assemblies. Nearly all operators expressed concerns regarding parts availability and the likelihood of aircraft downtime resulting from a parts shortage.

Significant provisions:

The FAA cites numerous reports of failure of the main landing gear pivots resulting in gear-up landings or loss of breaking as cause for the AD.
The proposed AD applies to Cessna 172RGs with the serial numbers 691 and 172RG0001 through 172RG1191 certified in any category.
The FAA estimates that cost of compliance will range from $1700 to $7600 per aircraft depending on the condition of the main landing gear pivot assemblies.
AOPA's search of the FAA's Service Difficulty Report (SDR) Database revealed 21 SDRs related to Cessna 172 RG main landing gear pivot assemblies over the past five years. Data indicating part total time, type of operation, and result of the "event" was not available in all SDRs.
Using the FAA's Small Airplane Risk Assessment Procedure (assuming the "worst case scenario" in lieu of data missing from the SDRs) AOPA determined that according to the FAA's own Airworthiness Concern guidelines an AD is not warranted to remedy this particular concern. The "worst case scenario" risk assessment calls for mitigating actions such as a Special Airworthiness Information Bulletin (SAIB) or GA Alert.
Cessna Service Bulletin SEB90-1 Revision 3, March 15, 1999 provides for other means to detect cracks other than those in the proposed AD Notice of Proposed Rulemaking No. 2000-CE-24-AD

AOPA position:

AOPA agrees that, in this particular situation, the potential for a cracked main landing gear pivot assembly to result in a gear-up landing or loss of braking action warrants an airworthiness concern. However, AOPA maintains that an AD mandating the inspection of main landing gear pivot assemblies and replacement of bushings is unnecessary and contradictory to the FAA's own internal Airworthiness Concern guidelines. AOPA believes that the FAA should adhere to the actions specified by the Small Airplane Risk Assessment as set forth in Appendix VI of the Small Airplane Directorate Airworthiness Directives Manual Supplement. AOPA maintains that this particular airworthiness concern would be best remedied through the issuance of an SAIB or GA Alert as set forth in the Small Airplane Directorate's Risk Assessment.

Status:

On October 30, 2000 the FAA issued NPRM 2000-CE-24-AD.
AOPA is currently working with aircraft type clubs such as the Cessna Pilots Association and the Cessna Owners Organization to construct comments in opposition of the issuance of an AD.
On December 5, 2000 AOPA sent comments to the FAA Rules Docket opposing AD action in favor of the issuance of a Special Airworthiness Information Bulletin or GA Alert using the known data and citing the FAA AD Handbook Supplement.
On March 28, 2001 FAA published final rule AD 2001-06-06.