NTSB Factual Report

HISTORY OF FLIGHT

On June 28, 2004, at 1439 Pacific daylight time, a Socata TB-20, N110U, collided with a berm during a forced landing following a total loss of engine power during cruise flight near Perris, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot and four passengers were not injured. The airplane sustained substantial damage. The personal cross-country flight departed French Valley Airport, Murrieta, California, about 1400, with a planned destination of Reno, Nevada. Visual meteorological conditions prevailed, and a flight plan had not been filed. The wreckage was at 33 degrees 48 minutes north latitude and 117 degrees 25 minutes west longitude.

During a telephone interview with a National Transportation Safety Board investigator, the pilot stated that after the initial climb, he leveled the airplane out at 10,500 feet mean sea level (msl). While configuring the airplane for cruise flight, he scanned the cockpit gauges and noticed that the oil pressure needle was in the yellow-green arc transition area, indicating a loss of pressure. He also noted that the oil warning light was flickering intermittently. He opted to return back to French Valley and contacted Ontario Approach advising them of his new itinerary. About 5 minutes after the call, the engine started to vibrate, and subsequently seized, making a loud bang. Smoke emitted from the engine and entered the cockpit area.

The pilot further reported that the airplane began to descend about 1,000 feet per minute, and he selected a dirt field to perform an emergency landing. During the landing roll, the airplane impacted a berm; the nose gear collapsed, and the airplane came to rest on its nose. After egressing the airplane, the pilot measured the landing ground scar to be about 1,100 feet. The airplane incurred damage to the nose gear and the left wing.

PERSONNEL INFORMATION

The pilot reported that during the 90-day period preceding the accident, he had flown about 16 hours, all of which were in the accident airplane. His cumulative flying experience totaled 1,018 hours, of which 919 where in the same make and model airplane. The pilot's last flight review was satisfactorily accomplished in the accident airplane on September, 21, 2003.

AIRPLANE INFORMATION

The engine was a Lycoming IO-540-C4D5D, serial number L-22959-48A. In the Lycoming Operator's Manual, the indicated oil sump capacity for the engine is 12 quarts, with the minimum safe quantity in the sump 4 quarts. It also stated that the normal operating oil pressure should be at maximum 90 pounds per square inch (psi) and at minimum 60 psi.

TESTS AND RESEARCH

Oil Leak Documentation.

Safety Board investigators and an investigator from Textron Lycoming, who was a party to the investigation, conducted an engine examination at Aircraft Recovery Services, Littlerock, California. The tachometer revealed a total time of 1,782.15.

Investigators attempted to drain residual oil from the engine's oil sump, but recovered no oil. They examined the engine and its accessories in an effort locate the source of the oil leak.

The engine's crankcase was cracked in numerous locations, with a hole about 3/4 inch in diameter located at the top of the crankcase, near the number 2 cylinder. Oil residue was sporadically dispersed on the exterior of the engine and on the accessory case. Investigators found no evidence of broken or disconnected hoses. The top of the engine cowling showed a concentration of oil near the firewall on the left side, which is the approximate location of the vacuum pump.

Removal of the vacuum pump, revealed an oily film on its gasket, part number AS3491-01 (seated between the vacuum pump flange and the engine accessory case flange). The film coated the lower portion of both sides of the gasket (see photographs showing the gasket). Also noted were small pieces of foreign debris on both the surface of the gasket and vacuum pump flange.

Logbooks and Maintenance History.

A review of the airplane's logbooks revealed that the vacuum pump had been installed at a tachometer time of 1,781.6, about 0.5 hours prior to the accident.

A Safety Board investigator interviewed, by telephone, an airplane mechanic at French Valley Aviation, Murrieta, the Federal Aviation Administration certified maintenance facility that performed the installation of the vacuum pump. The mechanic reported that he installed the pump with the gasket that was supplied with the pump.

The manufacturer of the vacuum pump, Rapco, Inc., supplies a gasket (part number AS3491-01) with their pump. In the TB-20 parts manual, the airplane manufacturer specifies that the gasket required is part number Z00.N7423254013, which they cross-reference with Textron Lycoming part number 8313. Despite numerous attempts, a Safety Board investigator was unable to cross-reference the gasket AS3491-01 with gasket 8313.

ADDITIONAL INFORMATION

The Safety Board investigator released the airplane wreckage to Aircraft Recovery Services on July 8, 2004.

NTSB Probable Cause

A loss of engine power due to oil exhaustion as a result of the mechanic's use of an incorrect gasket during the installation of the vacuum pump.