NTSB Factual Report

On May 06, 2016, about 1200 Pacific daylight time, an ANTONOV AN2 airplane, N2AN, sustained substantial damage during a forced landing, following a reported loss of engine power during approach to the San Bernardino International Airport, San Bernardino, California. The airplane was owned by the American Airpower Heritage Flying Museum, and was being operated by the pilot as a familiarization flight under the provisions of 14 Code of Federal Regulations Part 91. The commercial pilot and sole passenger were not injured. Visual meteorological conditions prevailed and no flight plan had been filed for the flight. The airplane departed the Cable Airport, Upland, California, about 1145.

In a telephone conversation with the National Transportation Safety Board investigator-in-charge, the pilot stated that the flight was a familiarization flight for a new member of their chapter of the Commemorative Air Force. The flight departed the Cable airport and flew east along the mountains, headed to San Bernardino. They contacted the San Bernardino tower and were instructed to enter the crosswind for runway 24. As part of the before landing checklist, the pilot turned on the carburetor heat and switched the fuel tank selector to the right fuel tank. Shortly thereafter, the engine lost all power. The pilot attempted numerous times to restart the engine, but was unsuccessful.

The pilot realized that he would not be able to reach the airport, and decided to make a forced landing to a small field in a residential area. During the landing approach, the airplane contacted a power line. After touching down in the field the airplane nosed over and came to rest inverted, which resulted in substantial damage to the wings and fuselage.

During the NTSB examination of the airplane, about 16 ounces of water was removed from the fuel system. Water was present in the lower gascolator, the fine fuel filter (upper gascolator), and subsequent fuel line to the carburetor inlet. A brass screen at the carburetor inlet and 2 carburetor fuel bowl thumb screens also contained corrosion, water and rust. (See Photo 1.)

The approved aircraft inspection checklist called for washing the carburetor and main fuel filter every 50 hours and cleaning and/or replacing the fine fuel filter every 100 hours. The fine fuel filter located halfway up the firewall on the left side of the aircraft is not easily accessible and not in a position to be drained prior to flight. The mechanic that completed the most recent inspection stated that he did not drain or check the fine fuel filter. The last logbook entry that specifically stated the fuel filters were cleaned was in September 2012.

NTSB Probable Cause

The mechanic’s failure to inspect the fine fuel filter gascolator as required during the most recent inspection, which resulted in a total loss of engine power due to fuel contamination.