27th of July 2019, Hydraulic failure, Blog #714
- V2Aviation
- Jul 28
- 2 min read
Updated: Jul 29
A Swearingen SA227 AC was scheduled to operate a training flight on the 27th of July 2019, to train two pilots for their first officer duties. (a Title 14 Code of Federal Regulations Part 91 instructional flight). Onboard the aircraft, the captain (instructor) and two co-pilots under training. One observing, one flying. After an uneventful take-off the landing gear was retracted, the aircraft was subsequently configured for a (practice) instrument approach, which would be followed by a missed approach. The instrument approach was flown without remarks; however, when executing the missed approach, the left main gear failed to retract, and the in-transit light remained illuminated. The right main and nose landing gears retracted normally. A scan of the instruments revealed that both the hydraulic system's low-pressure warning lights subsequently illuminated.
The emergency checklist was consulted, and the manual gear extension procedure was performed, without success. With all options exhausted, the captain took control and landed the aircraft with the left main landing gear partly extended. During the landing roll, the aircraft settled on its left-hand wing, after which the crew was unable to keep the aircraft under control. The aircraft left the paved area of the runway and collided with an airport sign before coming to a stop. Damage to the aircraft was substantial, and the crew did not sustain any injuries.
When the aircraft was inspected after the accident, the hydraulic reservoir was found empty, with hydraulic fluid being found in the left main landing gear wheel well. After recovery, the hydraulic reservoir was refilled. The left main landing gear drag brace was found to have failed, causing the failure of the landing gear to extend. The drag brace was replaced. When the hydraulic system was pressurised, no leaks were found in the landing gear system; a hydraulic leak was found in the hydraulic line to the left flap, which was a result of the accident. Airplane maintenance records indicated that hydraulic fluid leaks in the left main landing gear wheel well were noted on June 25th and again on 26th, about 30 days before the accident flight. These were repaired, and the airplane was returned to service. On June 30th, the hydraulic fluid level was low and was replenished. About 30 hours of flight time elapsed between that maintenance action and the accident.
The National Transportation Safety Board investigated the accident and concluded the probable cause(s) of this accident to be:
Failure of the left main landing gear to fully extend due to a lack of hydraulic fluid and during emergency extension procedures, which resulted in the collapse of the landing gear during landing and the subsequent runway excursion and collision with a sign.
The NTSB report, which served as the source for this blog, can be accessed by clicking on the .pdf file below;
Comments