This July 2007 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 172RG.
Location: Roche Harbor, Wash.
Aircraft damage: Subtantial.
What reportedly happened: The pilot was on approach when the airplane had an electrical failure. Concerned about the potential for an electrical fire, he elected not to attempt to troubleshoot the malfunction.
He extended the landing gear by placing the gear lever in the “DOWN” position, and visually confirmed that the gear was in place by looking into the mirrors affixed to the wings, as the landing gear indicator lights in the cockpit were not illuminated due to the loss of electrical power. The loss of electrical power rendered the landing gear warning system inoperative.
The pilot did not use the emergency gear extension system, which consists of a manual hydraulic pump per the checklist. When the airplane touched down the main landing gear collapsed.
No evidence of mechanical malfunction was found during an examination of the landing gear and alternator/battery electrical system. Investigators surmised that had the pilot used the emergency gear extension system per the procedures prescribed in the pilot’s operating handbook, the landing gear probably would have extended and locked. The underlying cause of the electrical system failure could not be determined.
Probable cause: The pilot’s failure to perform the emergency landing gear extension procedure prior to landing. A contributing factor in the accident was the failure of the electrical system.