NTSB Factual Report

HISTORY OF FLIGHT

On May 19, 2001, about 1032 Pacific daylight time, a Beech M35, N9820R, collided with ground obstructions during a forced landing at North Las Vegas, Nevada. The forced landing was precipitated by a loss of engine power. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, received fatal injuries. The airplane sustained substantial damage. Visual meteorological conditions prevailed, and no flight plan had been filed. The local area personal flight originated at 1020.

An owner-assisted annual inspection was recently accomplished on the accident airplane. The accident flight was the second flight following the annual. The owner changed the oil and filter element. About 10 minutes after departure, the pilot contacted the North Las Vegas (VGT) Air Traffic Control Tower local controller stating that he had no oil pressure and he was returning to land. The airplane was cleared to land and subsequently crashed about 1/2 mile west of the airport. On-site examination by Federal Aviation Administration (FAA) inspectors of the wreckage revealed the engine oil filter element was hanging free from the filter base by the safety wire, and fresh oil was observed covering the fuselage underside.

According to the Aircraft Maintenance Technician with FAA Inspection Authorization (A&P/IA) who approved the annual inspection, the pilot/owner had recently commented to him that other filter elements could be used besides the CH43109 element. You could either unscrew the 3/4-16 shaft from them, or the ones without a shaft could be screwed onto the Airwolf shaft. After the Airwolf system was installed, the owner routinely changed his own oil and filter element. Local friends and observers at VGT described the pilot as a brilliant engineer and a "tinkerer," who enjoyed fixing or repairing things he would find or obtain in his hangar/shop. The accident oil and filter element were changed after the annual inspection (May 4), about 1-hour flight time afterwards. The changed element was taken to the A&P I/A, to be cut open for inspection. No mention was made in the log records as to the new element change and whether or not their were any problems with the installation.

PILOT INFORMATION

Examination of the pilot's logbook revealed a total flight time carried forward on one page of 3,250 hours, and additional flights totaling about 79 hours more were noted. The last documented flight review occurred on January 22, 2001.

AIRPLANE INFORMATION

According to logbook information, the last recorded annual inspection occurred on May 4, 2001, at a tachometer reading of 4,293.04 hours. At the time of the accident, the recording tachometer indicated 4,294.07 hours. On February 2, 1998, an Airwolf Filter Corporation remote located oil filter was installed on the airplane at a tachometer reading of 4,076.54. According to Airwolf, the installation consists of a gold anodized base, which in this installation, was attached to the firewall. A 3/4-16 threaded shaft on which the filter elements are screwed, is permanently factory installed to a depth about 5 threads with red Locktite and torqued to the filter base.

WRECKAGE AND IMPACT INFORMATION

The Safety Board did not view the accident site. According to the FAA Las Vegas Flight Standards District Office, the airplane collided with a street light pole on approach to an open residential area, severing the left wing about midspan. The airplane came to rest inverted, and there was no fire.

On May 30, a post accident examination of the airplane occurred at VGT. The Airwolf oil filter base and Champion filter element were examined. Investigators noted that the installation location was in the aft engine compartment on the forward side of the firewall, and that someone installing a filter element could not see this location. Installation of a filter element would require a blind insertion of the element onto the threaded shaft by feel only. Examination of the gold anodized filter base revealed evidence of thread damage to the first complete thread. The first 5 or 6 threads of the shaft were damaged, with a cross the thread appearance to the first 2 or 3 threads. Other threads were damaged and had the appearance of attempted file repair. Both ends of the shaft exhibited internal damage to the bore of the shaft.

The FAA Service Difficulty reporting database was queried with no similar separation of the shaft from the base. The manufacturer reported no separations of the shaft from the bases.

MEDICAL AND PATHOLOGICAL INFORMATION

On May 20, 2001, the Clark County Medical Examiner performed an autopsy on the pilot. During the course of the procedure samples were obtained for toxicological analysis by the FAA Civil Aeromedical Institute in Oklahoma City, Oklahoma. The analysis were negative for carbon monoxide, cyanide, ethanol, and drugs.

ADDITIONAL INFORMATION

The Safety Board did not take possession of the airplane wreckage.

NTSB Probable Cause

The pilot/owner's failure to correctly install the oil filter, which resulted in oil exhaustion and a loss of engine power. Also causal was his attempt to modify the design of the oil filter element adapter by breaking the bond between the base and the threaded shaft, which resulted in a loss of torque during filter element installation.