What happened
On 14 February 2023, a Piper Archer III PA28-181, registration 9M-SKJ, was conducting a routine general handling training flight near Malacca International Airport. The flight, operated by Malaysian Flying Academy, involved a flight instructor and a student pilot. After completing several training exercises, the aircraft was transitioning toward a practice force landing when the crew noticed significant engine vibrations.
Shortly after passing the Chin Chin reporting point, the engine RPM dropped from 2,300 to 1,700. Despite attempts by the instructor to maintain altitude and advance the throttle, the engine failed to respond. When the crew attempted to use the alternate air setting as part of an engine roughness checklist, the RPM plummeted further to below 1,0 and continued to decline. With the engine losing power and the aircraft descending below 1,000 feet, the student pilot secured the engine, and the instructor executed a forced landing in an open construction area in Jasin. There were no injuries to the crew and no damage to the aircraft or surrounding property.
The investigation
AAIB Malaysia conducted a thorough examination of the engine systems, including the fuel injection servo, air bleed nozzles, and flow divider. Investigators analyzed Engine Indicating System (EIS) data, which initially showed a reduction in Exhaust Gas Temperature (EGT) in cylinder number three, suggesting inefficient combustion. However, subsequent physical inspections and pressure tests by the manufacturer's service provider found no obstructions or leaks. A visual inspection of cylinder number three also revealed no abnormalities. Ultimately, the investigation could not conclusively determine the specific cause of the power loss, as engine run-up tests following the incident showed no signs of vibration or power fluctuations.
Findings
- The engine power loss was likely preceded by inefficient combustion in one cylinder, though the exact trigger remains unidentified.
- The crew utilized "EFATO" and "Trouble Checks" from the operator's internal standard operating procedures (SOP) rather than the manufacturer-approved checklists.
- The operator's internal emergency checklists contained redundant and unapproved procedures that differed from the Piper Archer III Pilot’s Operating Handbook (POH).
- The aircraft was properly maintained, and the crew was medically fit and properly licensed for the flight.
Safety action
- The operator is advised to review its Standard Operating Procedures to eliminate confusion caused by redundant checklists.
- Any new emergency checklists incorporated into the operator's SOP must be officially approved by the manufacturer, Piper Aircraft Inc.
- The operator should implement a monitoring program to track engine performance for similar occurrences.