Cessna R182 N9077C accident near Lake City, Florida

Probable cause

Internal failure of the main electrical contactor, which resulted in a complete loss of electrical power and an inability to extend the landing gear through normal means.

NTSB analysis

The private pilot stated that, while on a cross-country flight, he noted that the airplane was losing electrical power and decided to make a precautionary landing. The pilot attempted to extend the landing gear and advised air traffic control of the emergency before all electrical power was lost. Since electrical power was lost before the landing gear extension cycle completed, he was unable to verify that the landing gear was down and locked in place, as the gear position indicator light would not illuminate due to the loss of electrical power. The pilot also referenced the manufacturer's emergency checklist for "Landing Without a Positive Indication of Gear Locking" and visually confirmed that the gear appeared to be fully extended. Upon touching down on the runway, the main landing gear collapsed, and the nose gear remained extended.

Postaccident examination of the airplane revealed that the cause of the electrical power failure was the main electrical contactor, which had shorted out internally and burned. The part was original to the airplane and had accrued about 3,235 total hours.

The landing gear was extended and retracted by hydraulic actuators operated by an electrically-driven hydraulic pump. It is likely that, when the pilot moved the landing gear selector to the down position, the extension cycle did not complete due to the loss of electrical power, resulting in insufficient hydraulic pressure to fully extend and lock the gear. The airplane was equipped with an emergency gear extension handle that would have allowed the pilot to manually complete the extension; however, the checklist that the pilot used did not instruct the pilot to manually lower and lock the gear. If the checklist had included the use of the emergency landing gear extension procedure, the pilot would likely have been able to manually increase hydraulic pressure in the system and avoid a gear collapse on landing.

Text from the NTSB. Open the NTSB docket for ERA16LA190 for the full record.