East Falmouth, MA, USA
N8DV
J. Schilling S-19
The pilot reported that, during the landing flare, the experimental, amateur-built airplane "ballooned." He then relaxed back pressure on the control stick to correct; however, the airplane then struck the runway hard and departed the left side. Examination of the wreckage revealed that the stabilator trim tab (antiservo tab) push-pull tube's threaded end had separated from its connection, that the associated nut remained loose on the threads, and that the three end threads were stripped. Further examination revealed that only three of the threads in the push-pull tube's threaded end were engaged in the trim tab connection and that about 1 inch of the threaded portion of the push-pull tube was exposed and visible on the opposite side of the securing plain nut. The kit manufacturer's assembly manual cautioned that a minimum of ten threads must be engaged to secure the stabilator trim tab push-pull connection. The manual also stated that about 0.5 inch of the threaded end of the push-pull tube should be exposed and visible on the opposite side of the securing plain nut. The builder assembled the airplane from a kit, and it was issued a special airworthiness certificate about 20 months before the accident. The pilot purchased the airplane from the builder about 5 months before the accident. At the time of the accident, the airplane had accumulated 94.5 total flight hours. The pilot performed the last condition inspection about 4 months before the accident, which was 32.8 total flight hours before the accident. The excessive thread exposure on the opposite side of the securing plain nut would have been detectable during the most recent condition inspection; however, the pilot/owner failed to detect the excessive thread exposure during the inspection.
On September 15, 2015, about 1350 eastern daylight time, an experimental, amateur-built Rans S19, N8DV, was substantially damaged while landing at Falmouth Airpark (5B6), East Falmouth, Massachusetts. The sport pilot was not injured. The airplane was registered to and operated by a private individual as a personal flight conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the flight that originated from Spadaro Airport (1N2), East Moriches, New York, about 1240.The pilot reported that during the landing flare to runway 25, the airplane "ballooned." The pilot relaxed back pressure on the control stick to correct, but the airplane then struck the runway hard and departed the left side. The airplane subsequently nosed over in soft grass and came to rest inverted. Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed damage to the vertical stabilizer, nosegear, and left wingtip. The inspector also noted that the stabilator trim tab (anti servo tab) push-pull tube threaded end (P/N KPTR0061) had separated from its female connection (P/N KPTR0062) with the associated nut remaining loose on the threads. The inspector observed the three end threads stripped. Another FAA inspector stated that when he compared the connection on the accident airplane to the kit manufacturer's assembly manual (Figure 08C-10), he noted that the manual depicted about a .5-inch portion of the threaded push-pull tube end inserted into the female connection, with .5-inch of the threaded portion remaining exposed and visible on the opposite side of the securing plain nut. However, the connection on the accident airplane was three threads inserted into the female connection, with 1 inch of the threaded portion of the push-pull tube remaining exposed and visible on the opposite side of the securing plain nut, indicating that about .5 inch more threaded portion should have been inserted and secured into the female end to withstand the loads incurred at the connection. This discrepancy could have been detected during a condition inspection. Further review of Figure 08C-10 revealed, "CAUTION: THREADS MUST BE ENGAGED A MINIMUM OF 10 FULL THREADS." The airplane had been assembled from a kit and issued a Federal Aviation Administration (FAA) special airworthiness certificate on January 8, 2014. The pilot purchased the airplane from the builder on April 23, 2015. At the time of the accident, the airplane had accumulated 94.5 total hours of operation. The pilot further stated that he performed the last condition inspection on May 6, 2015, which was 32.8 hours of operation prior to the accident. The pilot had accrued 558 hours of total flight experience, which included 37 hours in the accident airplane. The pilot's recent flight experience included 27 hours during the 90-day period preceding the accident; of which, 10 hours were flown during the 30-day period preceding the accident. All of those hours were flown in the accident airplane. The recorded wind at an airport located about 5 miles north of the accident site, at 1355, included wind from 290 degrees at 8 knots.
The experimental airplane builder's failure to properly secure the stabilator trim tab push-pull tube’s connection, which resulted in the tube’s separation and a subsequent hard landing. Contributing to the accident was the pilot/owner's failure to detect the improperly secured connection during a recent condition inspection.
Source: NTSB Aviation Accident Database
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