What happened
On October 4, 2001, a Cessna 177RG, registration OB-1332, operated by Aero Condor, was conducting a test flight over the Ica aerodrome. While climbing to the authorized flight level of 060, the aircraft reached approximately FL 040 when the pilot heard abnormal engine noises and notified the tower of an emergency descent.
During the approach to runway 33, the pilot observed that while the main landing gear (MLG) had extended, the cockpit indication light failed to illuminate. The pilot attempted to cycle the gear by retracting it and then extending it again, which successfully completed the extension cycle. This procedure disrupted the approach, leaving the aircraft at an excessive altitude for a safe landing on runway 33. Consequently, the pilot opted to divert the approach to runway 15, as the engine still possessed sufficient power for the necessary maneuvers.
During the final approach to runway 15, the engine RPM decreased significantly. This loss of power forced an immediate landing at low speed and with reduced control. Upon touchdown, the aircraft veered off the left side of runway 15, striking an earthen mound. The impact propelled the aircraft into an agricultural field parallel to the runway, resulting in major damage to the aircraft. There were no fatalities or injuries reported.
The investigation
The investigation focused on the engine's performance and the mechanical failures leading to the power loss. It was noted that the aircraft had recently undergone maintenance to address previous reports of a right magneto drop and slightly high cylinder head temperatures (CHT) during climb. The investigation examined the maintenance performed on the dual Bendix magneto.
Findings
- The investigation established that the dual Bendix magneto was failing to produce a spark for proper fuel combustion.
- The root cause was identified as improper torque application when replacing the magneto points; the points were not tightened according to the engine service manual specifications, causing them to stick and preventing the spark necessary to complete the engine's combustion cycle.