SAIB Issued For Cessna 177, 177A, 177B, 177RG, And F177RG Airplanes.

During a recent inspection of a Cessna Model F177RG airplane, two cracks were found visually in the wing spar cap; one was 1.22 inches in length and the other was 1.10 inches in length. Using eddy current inspections, three more cracks were found nearby, all at fastener holes. These three cracks were smaller measuring 0.167, 0.078, and 0.104 inches in length. The airplane is used for pipeline patrol and had 8,892 flight hours when the cracks were discovered.

Textron Aviation has issued Cessna Service Letter SEL-57-03 on November 19, 2015, addressing this concern with inspections for cracks and corrosion since corrosion may be a contributing factor in crack development.

In 2012, the FAA received eight reports of cracks in Cessna 210 wing spars. As a result of these reports, the FAA issued Airworthiness Directive (AD) 2012-10-04, which became effective June 5, 2012. This AD requires a one-time inspection for cracks of the wing spar on Cessna Model 210 airplanes.

Although the wing design of the Cessna Model 177 airplanes is similar to the wing design of the Cessna Model 210 airplanes, the airplane experiences lower aerodynamic loads and, therefore the FAA did not include the Cessna Model 177 airplanes in the AD since we had no reports of cracks on these airplanes.

Cessna manufactured over 4,000 of the Model 177 airplanes since 1968 and to date we have only received the above mentioned report of a wing spar crack on Model 177 airplanes. The FAA continues to monitor service difficulty information on the fleet.

The FAA has issued an SAIB recommending visual inspections of the wing lower spar caps for cracks and corrosion using procedures and inspection intervals documented in Cessna SEL-57-03. Special emphasis should be given to airplanes operating in extended low altitude operations (i.e., pipe line survey, surface spotting, sight-seeing, etc.) and those that have been approved for gross weight increase as well as airplanes with wing modifications, the FAA says.

If corrosion is found, wing spar repair information is available from Textron Aviation, as specified in Cessna SEL-57-03. If cracks are found, the wing spar should be replaced.

(Image from file)

FMI: SAIB