During a high-speed taxi test, a PIO caused the YF-16 to accidentally take off. The aircraft was piloted by Phil Oestericher. The purpose of the taxi test was to perform a function check of various aircraft systems. The test aircraft was fitted with AIM-9 sidewinder missiles on the wingtip pylons, it weighed 12,200lbs and had a CG of 34.4% MAC. During the taxi test, periodic application of the brakes was needed to prevent speedup. The nosewheel steering is disengaged beyond 50 kts as it is too sensitive. During this test, it was determined that while holding full breaks, the wheels started to slide at 87% power. The PIO had 10 oscillations in 14.3 seconds involving full lateral commands (50 deg/s), and caused the right stabilator and the left AIM-9 to strike the runway. During the PIO, rate and position limits of the control system was reached. Due to the deviation from the runway heading, the pilot made the decision to fly out of the condition. During landing a rudder doublet was performed to identify lateral stability. Due to this incident, it was discovered that the flaperon roll gain was higher than necessary. This happened in Fort Worth in 1974.[3] This PIO was first observed in the NT-33A in-flight simulations but was overlooked.[3]
[[F-16 Trailing Edge Flaperons]] -gains were automatically adjusted as a result of this event
Sidestick Controller – F-16 sidestick may have contributed to the event.[3]
Sources
- [1] B. J. Goszkowicz, “Sidestick Controllers During High Gain Tasks”.
- [2] RTO-TR-029
- [3] NATO, Ed., Flight Vehicle Integration Panel Workshop on Pilot Induced Oscillations: = (Atelier sur le Pompage Piloté). in AGARD advisory report, no. 335. Neuilly-sur-Seine: AGARD, 1995.
Backlinks
[[AIM-9 Sidewinder]]
[[Control Surface Rate Limits]]
[[Doublet Step Response]]
[[F-16]]
[[F-16 Trailing Edge Flaperons]]
[[NT-33A]]
Pilot-Induced Oscillations
[[YF-16]]