What happened
On August 19, 2008, at approximately 10:08 JST, a Cessna TU206F, registration JA3721, operated by First Flying Co., Ltd., performed a forced landing on a road in Shiki-cho, Yao City, Osaka Prefecture. The aircraft was conducting an aerial photography mission over the Osaka and Mie Prefectures when the pilot initiated a return to Yao Airport.
During the approach to Runway 27, the pilot began a descent and adjusted the engine settings. Following prior advice to mitigate engine issues experienced during low-power operations, the pilot activated the auxiliary fuel pump. While on the final turn, the engine lost power and stalled. Unable to reach the airport, the pilot identified a wide road as a suitable landing site. During the descent, the aircraft's left wing struck utility lines, and the aircraft eventually came to rest on the roadway. The aircraft was destroyed upon impact, though no fire broke out. The passenger sustained minor injuries, while the pilot escaped without injury.
The investigation
The JTSB investigation examined the aircraft's maintenance history, flight procedures, and the communication between the company's flight operations and maintenance departments. Investigators reviewed the Pilot Operating Handbook, which specifies that the auxiliary fuel pump should be in the OFF position during the final approach. The investigation also looked into the verbal instructions provided to the pilot regarding the use of the fuel pump to prevent vapor lock, a known issue during hot weather or low-power taxiing.
Findings
- The engine stall was caused by the pilot activating the auxiliary fuel pump during the approach, which created an excessively rich fuel-to-air ratio.
- A significant communication gap existed because maintenance issues and operational advice were shared via verbal instruction rather than through official aircraft logbooks or written reports.
- The pilot's decision to use the pump was influenced by a misunderstanding of when the pump should be engaged, as the flight operations supervisor's advice was interpreted as applying to the landing phase rather than just taxiing.
- The company's operational guidelines did not explicitly prohibit the use of the pump during descent, and the manufacturer's safety instructions regarding the pump's OFF status during approach had not been effectively communicated to all staff.