Cessna 177RG N747ML accident near Mesa, Arizona

Probable cause

The failure of maintenance personnel to properly secure the fuel supply line to the fuel flow divider, which resulted in a fuel leak, fuel exhaustion, and a total loss of engine power.

NTSB analysis

The pilot conducted an hour-long local flight to break in the newly-installed engine, and was returning to the airport for landing when the engine lost all power. After a failed attempt to restart the engine, the pilot initiated a forced landing into a water canal. The airplane impacted a berm and came to rest in the canal, resulting in substantial damage to the left wing and engine mount. About one cup of fuel was recovered from each fuel tank during recovery from the accident site.

Examination of the engine revealed that the fuel line from the fuel injection servo to the flow divider, which connected at the baffle union fitting on the aft side of the firewall, leaked when the engine-driven fuel pump actuated during the manual rotation of the propeller. The B-nut fitting could be tightened a half revolution until it seated onto the fitting by hand. There was no physical damage to the fitting, nor any accident-related impact damage within the surrounding area of the fitting.

Review of the task cards for the engine installation provided by the repair station indicated that the installation was completed and signed off by both a technician and inspector. Based on the available information, it is likely that the B-nut was not properly torqued onto the baffle union fitting and that, during the accident flight, the B-nut loosened, resulting in a fuel leak, fuel exhaustion, and a total loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR23LA017 for the full record.