Accident Overview
On December 10, 2010, at 1558 Pacific standard time, a Piper PA-28-140, registration N5800U, sustained substantial damage to its left wing during taxi after landing at Chino Airport in Chino, California. The airplane was operated by DuBois Aviation under Title 14 Code of Federal Regulations Part 91 as an instructional flight. Neither the student pilot nor the certificated flight instructor (CFI) reported any injuries.
Flight Details
The local instructional flight had departed Chino at approximately 1430. Visual meteorological conditions prevailed, and no flight plan was filed. According to the CFI, after performing a soft-field landing, the airplane did not taxi as expected. As they exited the runway, the airplane dropped onto its left wing and spun to the left.
Post-Accident Examination
Examination of the left main landing gear strut (part number 65319-3) by the NTSB investigator-in-charge revealed that the upper torque-link attachment lugs had detached from the landing gear strut. Additionally, the wheel assembly had separated from the strut and came to rest against the aft underside surface of the wing. The wing exhibited wrinkles on the upper and lower inboard skins, and three wing ribs were collapsed. Both pilots reported that the preflight inspection prior to the accident flight was uneventful, and no preexisting structural damage was noted.
Metallurgical examination of the landing gear strut and lugs at the NTSB Materials Laboratory showed that both lug separation surfaces had curving boundary features and areas of discoloration indicative of preexisting cracks.
Maintenance Records
New Piper Aircraft, Inc., had issued Service Bulletin (SB) 1131 on August 18, 2003, requiring visual and dye penetrant inspections of "cast" main landing gear strut cylinders at the next regularly scheduled maintenance event (or within 100 hours), and at 100-hour intervals thereafter until the cylinder was replaced with a new forged part. The subject cylinder was of the cast type, and its serial number fell within the SB's affected range. Review of the airplane's maintenance logbooks revealed that this Service Bulletin had not been performed.