On July 9, 2018, an APEX Diamond DA-40NG trainer aircraft, registration number B-88123, departed from Taitung Fung-Nian Airport to Kaohsiung International Airport for a training flight with one instructor pilot and 2 student pilots on board. The flight crew declared an emergency of engine failure to the traffic controller, then ditched on the sea about 12 nautical miles southwest of Kaohsiung International Airport. All of the three on board crew were rescued and sent to medication, the occurrence aircraft sank into the sea.

According to the Transportation Occurrence Investigation Act of the Republic of China, and referring to Annex 13 to the Convention on International Civil Aviation, the TTSB, an independent transportation occurrence investigation agency, started the investigation. The organization or agency been invited to join the investigation team included: Civil Aeronautics Administration of Ministry of Transportation and Communications and APEX. The Final Report was reviewed and approved by TTSB’s 5th Council Meeting on November 1, 2019.

Findings related to probable causes: The No.4 piston crown of the occurrence engine encountered a massive oil loss from the hole which caused by the abnormal thermal stress of non-optimal fuel injection, which all attributed to the deterioration of the injector interior cavitation, and eventually led the power loss and engine flame out.

Findings related to the risks: In accordance with the manufacturer engine manual, the occurrence engine has to be overhauled within the usage of 1,800 flight hours or 12 calendar days, before that, there was no maintenance action required on injector. As per the examination reports from the manufacturer, the risk of engine failure is raised due to the fuel injection of injector could deteriorate after 900 flight-hour usage.

Safety Recommendations

To Apex flight academy:

1. Draw up the checklist or relevant approaches to ensure the battery power of life vest is qualified and ready for use at any time.
2. Contact the aircraft manufacturer to propose the ADS-B OUT system upgrading modification, enhancing the integrity of the aircraft tracking information for the operating fleets.

To Taiwan Civil Aeronautics Administration, Ministry of Transportation and Communications:

1. Review the checklist or relevant approaches for ensuring the battery power of life vest is qualified and ready for use at any time which the Apex flight academy developed.
2. Review the Apex flight academy and other related operator to upgrade the ADS-B OUT system upgrading modification, enhancing the integrity of the aircraft tracking information for the operating fleets.
3. Evaluate the feasibility of adding transponder bases which the coverage is influenced by local geographic setting to enhance the dynamic monitoring on low altitude operating aircrafts.

Full investigation report is available for download at http://www.ttsb.gov.tw

Sherry Liu, Safety Investigator
Tel: 89127388-6286
Email:sherry@ttsb.gov.tw
Website: https://www.ttsb.gov.tw