WPR11LA070

During an instructional flight, the engine experienced a total loss of power. The flight instructor took over the controls and made a forced landing on a golf course. During the landing roll, the airplane nosed over into a sand trap, damaging the tail and fuselage. Postaccident examination of the airplane revealed a large amount of oil covering the underside of the fuselage. Examination of the engine revealed that the oil pressure line had failed just aft of the “B” nut that connected the line to the engine fitting resulting in the loss of all engine oil. Chaff marks were noted on the metal sleeve between the “B” nut and the flexible portion of the line. These chaff marks were the result of rubbing against the bottom side of the engine shock mount assembly. When the undamaged end of the oil line was installed on the engine fitting, it was noted that there was visible clearance between the line and the engine shock mount. It is likely that, with the engine operating, vibration resulted in contact between the line and the mount.

HISTORY OF FLIGHT On December 2, 2010, about 1030 Pacific standard time (PST), a Bellanca 7KCAB, N11858, made a forced landing following a total loss of engine power near Corona, California. Alliance International Aviation was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certified flight instructor was uninjured, and the commercial pilot undergoing instruction (PUI) sustained minor injuries. The airplane sustained substantial damage to the tail and fuselage. The local instructional flight departed Chino, California, about 0900. Visual meteorological conditions prevailed, and no flight plan had been filed. The instructor pilot reported that while returning to the airport the engine started running rough and losing power followed by a total loss of engine power. The instructor landed the airplane on a golf course fairway at the Cresta Verde Golf Course. During the landing roll, the airplane went into a sand trap and nosed over. During the recovery, it was noted that a large amount of oil was covering the underside of the airplane. A preliminary examination revealed a broken engine oil return line. On January 4, 2011, a post accident examination by Federal Aviation Administration inspectors revealed that the oil pressure line had failed at the nipple just aft of the b-nut. There were wear marks or chaffing marks on a metal sleeve, which is just aft of the b-nut prior to the flexible outer material. It was determined that these chaff marks were the result of rubbing against the bottom side of the engine load mount assembly. The undamaged end of the oil line was reinstalled on the fitting at the engine, and there was visible clearance between the hose assembly and the engine mount in the static condition. Review of the airplane’s maintenance records showed that the last time this engine was removed for overhaul was in 2003, and it had annual inspections every year since then. There was no record of this hose assembly having ever been inspected since overhaul. The failed component, MS24588 nipple, fractured circumferentially at the smallest (0.019"sq) cross sectional area of the part. There was no evidence of Service Difficulty Reports (SDR), Metadata Repository Report (MDR), or Special Airworthiness Information Bulletins (SAIB) history with this part.