SPLIT-FLAP ANYONE?

by Erroll Williams

I was in the final three months of Class 53B at Webb AFB, TX, flying the T-33, when the subject of a "split flap" was briefly discussed. I wondered if I would recognize the condition, and take corrective action to prevent a deadly outcome. However, the odds of this happening were so remote that I quickly dismissed it. Years later I would be put to the test.

Following three years flying the F-89 Scorpion, I returned to the 115th Squadron, California AirGuard at Van Nuys, where I flew several models of the F-86. On 27 February 1958, 1 was flying an F-86E. No other aircraft was with me as I entered the traffic pattern for runway 34. 1 made a normal pitch-out and selected FLAPS shortly before turning onto final. As the desired bank angle of 35-40° was reached, I centered the stick. But the bank angle kept increasing! The stick was at 'full right' with no effect. Impulsively, I slammed the flap control UP. To my relief I was again in control. A go-around was initiated and the tower informed me that I had likely experienced a "split flap". I flew down over the Santa Monica Mountains to check the flaps with lots of light from a full moon. Both flaps responded to "DOWN" control and I proceeded back for a normal landing. Appropriate entries were made on the Form 1.

The next day maintenance informed me that they could not duplicate a "split flap" condition, suggesting that I might have experienced an asymetrical speed brake extension.

The following weekend was our monthly guard duty. At the first briefing, Maj. Swift, our Air Force Advisor, mentioned my flight. He began by saying he had flight tested my aircraft as I had written it up for a .split flap' incident. He had climbed to altitude and checked the flaps. Everything was normal after two flap cycles, and he concluded that "Williams didn't know what the hell he was talking about!"

However, just to be sure, he cycled the flaps one final time. Moments later he found himself upside down with a -split-flap"! You'll recall that each flap had its own motor, with an interconnect between them to keep the flaps synchronized, and to allow one flap motor to operate BOTH flaps should either motor fail. In the case of my aircraft (and Maj. Swift's), it was found that the left motor operated intermittently. The redundancy of the interconnect was negated as it was found to be sheared. Therefore the flaps were operating independently.

My long dormant question from Class 53B was answered - I had taken timely action and survived.


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