History of the Flight
The aircraft, a Beech Bonanza C35 (N60256), was flown by its owner to test adjustments from recent maintenance, including the landing gear warning system. The test revealed that the landing gear warning horn activated at a higher throttle setting than intended. The pilot had limited time and called to rejoin the circuit 10 minutes after takeoff. Weather conditions were showery with gusty winds. The pilot flew a faster approach and delayed full flap selection due to wind conditions and time pressure. After landing, intending to raise the flaps to dump lift, the pilot inadvertently selected the landing gear UP. Realizing the mistake, he selected DOWN, but the gear had partially retracted. The aircraft slid to a halt on the runway, sustaining damage to the inner main gear doors, nose gear doors, nose gear leg assembly, and propeller.
Aircraft Examination
Examination on site and later functional tests under AAIB supervision showed that the landing gear system and warnings were serviceable. The landing gear safety switch was slightly out of adjustment, operating 1/8 inch before the normal setting, but this discrepancy was considered minimal. The circuit breaker had popped. When placed in an "on ground" condition, the gear drive motor did not operate, confirming the safety system's integrity.
Recorded Information
Radio transmissions captured the landing gear warning horn in two transmissions: one at about 1 minute 45 seconds prior to the accident and a five-second transmission at the time of the accident. Wind reports from ATC at about 90 seconds and 30 seconds prior did not include the warning horn.
Analysis
The investigation found that the accident occurred when the pilot inadvertently selected the landing gear UP after landing. The nature of damage suggested either a late extension sequence or that the aircraft was partially airborne when retraction began. The pilot believed the error was influenced by the similar flap and gear switches and the stress of the gusty conditions.