What happened
On 12 February 2011, a CASA 212-100, registration PK-ZAI, operated by PT. Sabang Merauke Raya Air Charter, departed Hang Nadim Airport, Batam, for a scheduled maintenance test flight. The flight was intended to verify the performance of the aircraft following the replacement of the number one engine. The crew consisted of two pilots and three company engineers.
While flying over the Tanjung Pinang area, the aircraft was cleared to climb to 4,000 feet. However, at 0644 UTC, the aircraft disappeared from radar tracking. Shortly thereafter, reports emerged of an aircraft crash in the Gunung Kijang forest on Bintan Island. The wreckage was located approximately 30 km north of Tanjung Pinang Airport. The impact resulted in five fatalities and substantial damage to the aircraft.
The investigation
The investigation examined the aircraft's maintenance history, the engine teardown, and the medical fitness of the flight crew. Investigators analyzed the engine performance, noting that the left engine had been shut down using standard ground procedures, while the right engine likely shut down via windmilling prior to impact.
Technical reviews of the aircraft's configuration revealed that a specific Service Bulletin regarding the anti-reverse system had not been incorporated. Furthermore, the investigation scrutinized the company's maintenance test flight protocols, finding that the procedures used were inconsistent with the requirements outlined in the manufacturer's manuals for single-engine changes. The investigation also focused on the medical certification process for the pilot in command, specifically regarding neurological examinations for pilots over the age of 60.
Findings
Several contributing factors led to the accident:
- The flight test was conducted without a properly prepared or detailed flight test plan.
- The pilot in command suffered from a vestibular lesion causing paralysis in the right vestibular organ, which likely rendered the pilot highly susceptible to spatial disorientation during flight maneuvers.
- The maintenance test flight procedures used by the operator did not align with the current requirements found in the CASA 212-100 and Garrett TPE331-5 maintenance manuals.
- There was a lack of oversight regarding the incorporation of necessary Service Bulletins, specifically regarding the anti-reverse system.
- Discrepancies were identified in the medical examination standards for older pilots, specifically concerning the interpretation of Video Nystagmography results.
Safety action
Following the accident, the Directorate General of Civil Aviation (DGCA) conducted a special safety audit of the operator and issued a safety circular instructing all Indonesian-registered aircraft operators to evaluate safety precautions before conducting maintenance practices in airport areas. The operator subsequently replaced several management positions to improve safety management systems and procedures.