SEA01LA104
SEA01LA104

On May 24, 2001, approximately 1445 Pacific daylight time, an experimental Curtis Lionheart was consumed by fire after experiencing a gear collapse during a landing at Bremerton National Airport, Bremerton, Washington. The airline transport pilot, who was the sole occupant, was not injured, but the aircraft, which was owned and operated by the pilot, was destroyed in the post-crash fire. The local 14 CFR, Part 91 maiden flight of the experimental aircraft, which was being conducted in visual meteorological conditions, departed the same airport about 45 minutes earlier. No flight plan had been filed.

After departing Bremerton National, the pilot flew around the area performing a series of preplanned maneuvers in order to determine the flight characteristics of the aircraft. By comparing the indicated airspeed of the subject aircraft to that of the chase plane during this series of maneuvers, the pilot was able to determine that the airspeed indicator in the Lionheart was indicating approximately 25 knots lower than it should have. Upon returning to the Bremerton Airport, the pilot made two preplanned low approaches, taking into consideration the apparent indicated airspeed error. According to the pilot, his first approach, executed at 70 knots indicated airspeed, was determined to be too fast. His next low approach, executed at 45 knots indicated airspeed, "looked good and felt good," so he decided to use 45 knots the next time around and terminate in a full-stop landing.

After viewing multiple videos showing the accident sequence, and interviewing witnesses who were present at the event, it was determined that on this third approach, as the aircraft passed a point approximately one-half mile from the approach end of the runway, it was at a higher altitude than it had been on the first two approaches. According to the pilot, he could see that he was going to "land beyond the spot I had picked out," so he elected to slip the aircraft in order to increase its rate of descent. As the aircraft passed the runway threshold, the pilot initiated the landing flare and began to eliminate the slip. After the aircraft leveled off above the runway surface and began to float during its deceleration to touchdown speed, it was tracking approximately parallel to the runway centerline. In addition, the pilot's control inputs to eliminated the slip had brought the longitudinal axis of the aircraft to a point where it was nearly aligned with the runway. But, during the last portion of the aircraft's pre-touchdown deceleration, its nose began rotating to the right. Then, just prior to touchdown, the aircraft's lateral axis experienced an additional significant clockwise shift.

At the moment the aircraft's main gear came in contact with the runway, it was tail-low and its lateral axis was cocked a significant degree to the right of the runway heading. Immediately after touchdown (within one second), the aircraft rocked up onto its left main gear and rapidly began rotating further to the right. As the aircraft passed a point approximately 275 feet beyond its initial touchdown point, the left main gear failed inward (direction of normal retraction). Immediately thereafter (within two seconds), the right main gear failed outward (opposite normal direction of retraction). At the instant the bottom of the right wing contacted the runway, a massive fire broke out that ultimately consumed the aircraft.

Further investigation determined that although the wind had been light and variable during most of the day, at the time of the accident, the landing was being executed in a tailwind of approximately five knots. Discussions with the pilot also revealed that in the last year, he had accomplished a total of four landings in tailwheel-equipped aircraft. Two of those landings were in were in a Cessna 185, and the others were in a Piper J-3 Cub. During this same period, the pilot had made no landings in a Lionheart.

During the investigation, the main gear legs and the gear actuator/down-lock mechanisms were inspected. The inspection revealed that during the accident sequence, both down-lock mechanisms (internal to the actuators) had remained locked, and the actuator rods had remained extended. It was also determined that on the left main gear, the 5/8 inch 17-4 stainless steel pin/bolt that attaches the actuator/down-lock rod to the gear housing had failed in overload. A review of the aircraft gear systems assembly disclosed that such a failure would allow the left main gear to retract inward (as it did in this sequence of events).

Inspection of the right main gear revealed that the gear leg and actuator/down-lock had remained intact (and locked), and that there were no failures in their structure or interconnection. Further inspection revealed that at the point where the top of the right gear leg attaches to the inboard rib/bulkhead of the right fuel tank, the gear leg had separated from the airframe, taking a portion of the rib/bulkhead with it. A further review of the gear system and the lower wing assembly detail drawings disclosed that separation of the right main gear leg in the aforementioned manner would allow the gear leg to pivot outward around the actuator attach point (as it did in this sequence of events), and would provide an opening for fuel to spill directly into the right main gear well.




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