What happened
On 20 June 2010, a Piper PA 34-200T, registered PK-SUV, was operating a charter flight from Halim Perdanakusuma Airport to Semarang Airport. The aircraft was carrying a pilot and three passengers. During the final approach to runway 13 at Semarang, the crew discovered that while the main landing gear had locked into position, the nose landing gear failed to extend.
The pilot initiated a go-around and attempted to deploy the nose gear manually using the free-fall control system, but the gear remained retracted. After requesting air traffic control to visually verify the gear configuration—which confirmed only the main gear was down—the pilot decided to return to Halim Perdanakusuma. To mitigate the risk of a gear-up landing on the primary runway, the pilot opted to land on a grass strip at runway 06. Before touchdown, the engines were shut down and the propellers were feathered. The aircraft successfully landed on the grass, traveling approximately 100 meters, but the impact caused damage to the nose section and bent the left engine propeller blades. There were no injuries among the four occupants.
The investigation
Investigators examined the aircraft's hydraulic system to determine why the manual extension failed. The inspection revealed the presence of debris within the hydraulic pipeline located between the nose landing gear actuator and the restrictor on the up-line pipe. Specifically, the investigation established that the dirt particles found were larger than the 0.31-diameter restrictor hole.
Findings
- The primary cause of the nose gear failure was that debris blocked the hydraulic flow at the 0.31-diameter restriction valve within the nose landing gear actuator's down-line.
- This blockage prevented the release of hydraulic pressure in the actuator's up-chamber, which rendered the manual free-fall extension ineffective.
- The source of the contamination within the hydraulic line could not be determined.
- The operator's approved maintenance program was unavailable for review during the investigation.
Safety action
Following the accident, the operator integrated a new safety action into its aircraft inspection and maintenance programs. The NTSC has recommended that the Directorate General of Civil Aviation (DGCA) review maintenance tasks related to hydraulic systems for Piper Seneca aircraft operated in Indonesia, and urged the operator to utilize an approved continuous airworthiness maintenance program.