M and M Aviation Aero Commander 500-B accident

On the dark early morning departure from Dallas Love Field, the pilot rated passenger was occupying the left seat. During climb out the pilot-in-command realized there was some kind of problem because they were not gaining any altitude, so he 'applied 1/4 flaps to try and gain some altitude.' The airspeed at that time was about 105 knots. He then retracted the flaps because his airspeed had deteriorated to about 90 knots and the aircraft was not gaining altitude. 'Both engines appeared to be developing power, RPM 2,300 Manifold Pressure 26 inches with fuel flow, however he thought the right engine acted as if it were operating only on one mag.' The pilot rated passenger did not notice any problems with the engines until after the airplane struck the first power line and then the right engine began making sounds like it was 'cutting out.' Examination of the aircraft wreckage revealed that both main landing gear were down and the nose landing gear was within the aircraft's crushed nose. The right main landing gear up lock was fractured. The landing gear control lever was found half way between the up and down position, the flap control lever was in the full down position, and the throttle, propeller and mixture control levers were full forward. Examination of the flap actuator revealed it to be fully extended and the exposed actuating rod was measured at 3 inches. According to the aircraft manufacturer, this would equate to the flaps being fully extended. Examination of the right engine revealed the right magneto's ignition lead cover plate was separated from the magneto. The magneto on the right engine was changed by the pilot the day prior at Tulsa, Oklahoma. Cracks were found in cylinders #1 and #4 of the right engine in the vicinity of their intake ports. The cracks were 2 inches in length with black deposits. It appeared that the intake ports had been modified. Performance data indicates the airplane's single engine rate-of-climb was approximately 289 feet per minute with an indicated airspeed of 108 miles per hour. To attain this rate of climb the aircraft's flight manual states that you must 'use maximum continuous power on operating engine (full throttle, 2,575 RPM) leaned to best power fuel flow, cowl flaps as required to control engine temperature within limits, landing gear up, flaps up. Inoperative engine feathered, cowl flaps closed. Climb at best rate of climb speed.'

Verbatim NTSB analysis and probable cause from the NTSB dataset