CEN21LA406

The pilot reported that before departing on a cross-country flight, he added 42 gallons of 100LL aviation fuel, which appeared to fill both inboard wing fuel tanks. He calculated a 17-gallon-per-hour fuel burn for the 2 hour and 45-minute flight. While in cruise flight, about 2.5 hours after departure, a total loss of engine power occurred. The pilot was unable to restart the engine, and he executed a forced landing to a corn field, which resulted in substantial damage to the fuselage and right wing. Postaccident examination revealed that both left and right fuel tanks were intact. The fuel filler necks and collars were removed from both wings for internal inspection of the rubberized, bladder fuel cells. The cell from the left tank exhibited minor wrinkling, but overall was still attached to the cell’s snaps and fittings. When the right cell was examined, it was discovered to be unsecured from the outboard and aft edges with the cell folded and wrinkled inboard to the outboard fuel filler neck. The investigation was unable to determine the extent to which the loose fuel cell bladders would have affected actual fuel quantity and unusable fuel. However, given the lack of malfunctions or anomalies noted during the examination and the lack of fuel present in the gascolator, it is likely that the engine lost power due to fuel exhaustion.

On September 6, 2021, about 1515 central daylight time, a Cessna A185F airplane, N7574N, sustained substantial damage when it was involved in an accident near Kingsley, Iowa. The pilot and passenger were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, before departure he completed his flight planning, and added 42 gallons of 100LL aviation fuel, which increased the total fuel on board to about 70 gallons, based on both tanks appearing full when he looked in the fuel filler port on the inboard wing fuel tanks. The pilot calculated a 17-gallon-per-hour fuel burn for the 2 hour and 45-minute flight. When the airplane was about 25 miles from his destination, a total loss of engine power occurred. Trouble shooting was unsuccessful, and the pilot executed a forced landing to a corn field, which resulted in substantial damage to the fuselage and right wing. The engine and propeller remained attached to the airframe and were undamaged. A post-accident engine test run took place on November 17, 2021. Before adding fuel to the airplane, the gascolator was examined and found to be absent of any fuel. Fuel was supplied from an external fuel tank into the fuel lines associated with the left wing. The engine started on the first attempt with no hesitations or anomalies noted. The throttle was advanced, and a magneto check was accomplished with a drop of 58 rpm from the left magneto and a 60 rpm drop from the right magneto. Postaccident examination revealed that both left and right fuel tanks were intact. The fuel filler necks and collars were removed from both wings for internal inspection of the rubberized, bladder fuel cells. The cell from the left tank exhibited minor wrinkling, but overall was still attached to the cell’s snaps and fittings. When the right cell was examined, it was discovered to be unsecured from the outboard and aft edges with the cell folded and wrinkled inboard to the outboard fuel filler neck as shown in figure 1. Figure 1: Right Fuel Cell Bladder The airplane was equipped with optional long-range fuel tanks. According to the Cessna 185 Owner’s Manual, the total unusable fuel for an aircraft equipped with long range fuel tanks is 6 gallons.