History of Flight
On July 27, 2009, about 1130 eastern daylight time, a Piper PA-34-200T, N1494X, operated by Air Transport Incorporated, was substantially damaged during landing at South Jersey Regional Airport (VAY), Mount Holly, New Jersey. The commercial pilot and his sole passenger were not injured. Visual meteorological conditions prevailed for the flight, which departed Princeton Airport (39N), Princeton, New Jersey, at approximately 1100. No flight plan was filed for the positioning flight conducted under 14 Code of Federal Regulations Part 91.
According to the pilot, he experienced a problem with the landing gear during several flights prior to the accident flight. He reported the GEAR UNSAFE light would remain illuminated through an entire cycle of lowering and retracting the landing gear. Additionally, during the flight preceding the accident flight, the GEAR UNSAFE light would not extinguish at all until the landing gear was fully extended.
The pilot advised the director of operations (DO) about the landing gear malfunction, and the DO instructed him to notify the director of maintenance (DOM) to troubleshoot the problem. On the day of the accident, the pilot queried the DOM on the status of the gear discrepancy. The DOM informed him that he had not looked at it yet, but would do so immediately. The pilot preflighted the airplane as the DOM inspected the landing gear. The DOM found a dirty switch and cleaned it, asking the pilot to advise if the problem was solved.
The pilot departed for VAY. When the landing gear was retracted, the gear unsafe light remained illuminated. At VAY, he entered the downwind leg of the traffic pattern for runway 26. When he extended the landing gear, the left main landing gear light did not illuminate. The pilot retracted and extended the landing gear several times until, after a short and unusual delay, the left main landing gear light illuminated. He presumed the gear was down and locked and landed uneventfully. After taxiing to the ramp, a post-flight inspection revealed substantial damage to the wing spar.
Personnel Information
According to FAA and pilot records, the pilot held a commercial pilot certificate with ratings for airplane single-engine land, airplane multi-engine land, and instrument airplane. His most recent FAA first-class medical certificate was issued on November 4, 2008. He reported 9,100 total hours of flight experience, and 3,650 hours in the accident airplane make and model.
Aircraft Information
The airplane was manufactured in 1975. Its most recent 50-hour service was completed on November 18, 2008, at 4,172.56 total hours. Unscheduled maintenance at 4,179.46 hours included replacement of both main tires and tubes and cleaning, inspection, and repacking of wheel bearings. A 100-hour inspection was completed on February 8, 2009; a retraction test of the landing gear in normal and emergency modes performed satisfactorily. The most recent 100-hour inspection was completed on May 26, 2009, at 4,310.0 total hours; the logbook stated only that an inspection was performed per the check sheet. The airplane's Daily Flight Log showed no discrepancies or corrective actions after July 23, 2009.
Meteorological Information
A weather observation at VAY about 24 minutes after the accident recorded calm winds, visibility 10 miles, few clouds at 2,200 feet, scattered clouds at 4,500 feet, temperature 26°C, dew point 21°C, and an altimeter setting of 29.98 inches of mercury.
Airport Information
VAY had one runway oriented 8/26. Runway 26 was asphalt, in good condition, 3,911 feet long and 50 feet wide. An obstruction (a tree 45 feet high) existed 909 feet from the approach end and 99 feet left of centerline, requiring a 15:1 slope to clear. A precision approach path indicator displaying a 3-degree glide path was installed on the right side of the runway.
Wreckage and Impact Information
Post-flight inspection by contract maintenance personnel at VAY revealed the left wing was at a higher angle than normal, the oleo strut extended farther than the right strut, and the left main landing gear had shifted in its mounts. Further examination showed the forward main landing gear support fitting for the left main landing gear truss had failed, and the gear had shifted approximately 6 inches from its normal mounting position. The lower trailing edge of the main spar passing through the left main landing gear well had a missing piece of metal about the size of a dime; the main spar web was deeply gouged; the false spar aft of the left main landing gear had a buckled lower cap; and there was a skin buckle immediately aft of the left main landing gear well.
Tests and Research
Examination by the NTSB confirmed that the left forward support fitting had fractured. Fracture surfaces were irregular, granular, and faceted, consistent with overstress separations in castings. Some pieces contained secondary part-through cracks, consistent with high stresses, and some surfaces showed smearing from post-fracture contact. No evidence of fatigue cracking or corrosion was found. In 1975, Piper Aircraft superseded landing gear support fittings 67041-0, -1, -2, and -3 with the symmetric 67041-4 fitting, which could be used on either side. There was no requirement to replace earlier parts. The fractured fitting might have been original to the airplane, as fragments were slightly thinner than other fittings, and the material appeared more consistent with A356 aluminum/silicon casting alloy than with the Almag 35 alloy specified for current parts. Review of manufacturer's drawings revealed that the fractured fitting predated the drawings.
Service Bulletin 956, released March 3, 1992, required support fittings on PA-34-200 airplanes to be replaced with fittings having larger diameter (0.312 inch) attachment holes. The Service Bulletin implied that PA-34-200T airplanes already had 0.312-inch diameter attachment holes. Examination of all fittings from the accident airplane showed mounting holes consistent with the larger diameter. The only action directed specifically at PA-34-200T airplanes was to clean and inspect the fittings using a dye-penetrant method, with cracked fittings to be replaced.