Incident Overview
On January 21, 2018, at 1304 eastern standard time, a Cessna 172RG airplane, registration N9415B, was substantially damaged during landing at Eastern West Virginia Regional Airport (MRB), Martinsburg, West Virginia. The flight instructor and private pilot aboard were not injured. The airplane was registered to Dulles Aviation, Manassas, Virginia, and operated by Av-Ed Flight School, Leesburg, Virginia, as a Title 14 Code of Federal Regulations Part 91 instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from Leesburg Executive Airport (JYO), Leesburg, Virginia, at about 1130.
Sequence of Events
The flight instructor reported that the purpose of the flight was to practice commercial pilot maneuvers and landings. The flight was normal, with approximately six short and soft-field takeoffs and landings completed without incident. On the seventh landing, after the private pilot extended the landing gear, the gear down-and-locked light did not illuminate. A visual check revealed that the nose gear was extended but the main gear was trailing and not fully extended.
The flight instructor stated that they used the manual emergency gear handle to attempt to pump the main gear down, but there was insufficient hydraulic pressure in the system to extend the gear. The instructor then landed the airplane with the nose wheel still extended. He reported being able to keep the airplane straight for about 600 feet, after which the left wing dropped, resulting in substantial damage to the wing and elevator. Following the landing, hydraulic fluid was observed pooling under the airplane and along the side of the empennage. The hydraulic reservoir was empty.
Postaccident Examination
A postaccident examination revealed that an O-ring had failed internally inside the right gear actuator, causing a hydraulic fluid leak. Since the landing gear is extended and retracted by hydraulic pressure, the leak prevented the system from maintaining adequate pressure for both the electric pump and the manual gear handle to extend the main gear.
Weather Conditions
At 1306, the weather conditions reported at MRB were calm wind, visibility 10 statute miles, scattered clouds at 3,900 feet, overcast clouds at 7,500 feet, temperature 13°C, dewpoint 5°C, and an altimeter setting of 30.12 inches of mercury.