NTSB Factual Report

HISTORY OF FLIGHT

On June 9, 2002, approximately 0925 Pacific daylight time, an experimental Lewis 7/8 scale Nieuport 11, N132DC, impacted the terrain during an attempted forced landing about 400 feet south and 60 feet west of runway 16 at Independence State Airport, Independence, Oregon. The private pilot was not injured, but the aircraft, which is owned and operated by a friend of the pilot, sustained substantial damage. The local 14 CFR Part 91 personal pleasure flight, which departed the same airport about 30 minutes earlier, took place in visual meteorological conditions. No flight plan had been filed. There was no report of an ELT activation.

According to the pilot, who's intention it was to evaluate the aircraft's handling and performance during this flight, this was the first time the Nieuport had been airborne after its construction was complete and its Special Airworthiness Certificate had been issued. After takeoff, he climbed to about 1000 feet above the ground (agl), and maneuvered near the airport while checking the engine instruments and flight instruments. After about 20 minutes, the pilot decided to start a climb in order to perform some additional maneuvers at a higher altitude. He therefore added power and raised the nose of the aircraft. After raising the nose, he noticed the airspeed decreasing as he had expected, but he also noticed that the altimeter indicated that the aircraft was staying at the same altitude. At that time he rechecked the tachometer reading, and discovered that the engine rpm had dropped down to 2,500. As soon as he saw the lower than expected rpm, he immediately turned toward the airport, with the intention of making a precautionary landing if necessary. After turning toward the airport, the pilot confirmed that the aircraft's oil temperature and oil pressure were within the acceptable range, and that there were no other indications of a problem except the reduction in rpm. According to the pilot, because there was no clearly suitable terrain between the position he was at and the airport, he decided to aim for a point about 200 feet south of the approach end of runway 16. By the time the aircraft was half way back to the airport, the engine rpm had dropped to 2000, and the aircraft would no longer maintain altitude. As the pilot continued toward the airport, he realized that there were a set of power lines that he would have to clear, but based upon the aircraft's apparent rate of descent, he elected to continue. Ultimately the aircraft passed over the power lines while it was still about 250 feet in the air. As he passed over the wires, the pilot rechecked the tachometer and discovered that the rpm was down to 1,500. Soon thereafter, it became clear that the aircraft would not be unable to reach the runway, and that the pilot would have to attempt to land on an area of short grass alongside the runway surface. According to the pilot, he then stretched the glide as long as he could, and then attempted to turn to parallel the runway because there was a depression that ran along the runway that kept him from trying to land perpendicular to the runway heading. The pilot said that in an attempt to fly past the unsuitable terrain, he waited as long as possible to turn parallel to the runway, and because he had lost so much altitude, as he tried to execute the turn to the desired landing heading, the aircraft’s lower right wing impacted the terrain.

METEOROLOGICAL INFORMATION

According to the pilot, at the time of the accident he estimated the temperature to be 70 degrees Fahrenheit, with 40 miles visibility, and scattered clouds about 2,000 agl. He said there was no precipitation, and no restrictions to visibility.

The 0953 surface aviation weather report (METAR), taken at Salem, Oregon, which is located about 10 miles northeast of Independence, indicated scattered clouds at 1,700 feet agl, winds from 150 degrees at 8 knots, temperature 56 degrees, dew point 49 degrees, and an altimeter setting of 30.18 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

The aircraft impacted the mowed grass terrain about 400 feet south and 60 feet west of the approach end of runway 16, and ultimately came to rest inverted. All portions of the aircraft structure and systems were accounted for at the accident site. The lower right wing was bent upward about 10 degrees just outboard of the wing interplane strut, and the upper left wing tip bow had been pushed inward. The main landing gear structure had partially collapsed, and the rudder (the aircraft has no vertical stabilizer) was bent 90 degrees to the right, and was laying on top of the right horizontal stabilizer. The lower right longeron was bent at the gear attach fitting, and the left side of the engine cowing had been crushed aftward. Both blades of the fixed-pitch wooden propeller had fractured, and pieces of the blades were located in the area immediately around the impact area.

The number three and four exhaust stacks contained oil deposits, and the number three spark plug had oil deposits on its electrode. All four spark plugs displayed normal wear (new). The oil screen was pulled and was found free of deposits. The piston and cylinder walls on both the number three and four cylinders showed minor scuffing, and there was a broken compression ring on the number three piston. The remnants of the propeller was pulled through by hand, and valve train and accessory drive continuity were verified.

During the inspection of the engine, it was determined that the distributor position locking clamp bolt was loose, and the distributor was easily rotated by hand. It was also determined that rotation of the distributor while in flight would change the timing of the engine and reduce its potential to produce power. During a discussion with the project manager for the manufacture of this aircraft, he said that he felt quite sure that when the engine was first assembled and the static timing adjustment was set, the distributor position locking clamp had been tightened. He further stated that although the clamp was tightened at that time, it had later been loosened during a pre-installation engine test run in order to perform a dynamic timing adjustment. It was his belief that since for safety reasons the final tightening of the clamp had to be performed after the engine was shut down at the end of the test run, that step had simply been overlooked.

Except for the ability of the distributor to freely rotate while the aircraft was in flight, there was no other evidence of a malfunction or anomaly that would have contributed to the significant reduction in power that occurred during the subject flight.

ADDITIONAL DATA AND INFORMATION

The aircraft was released to the owner, Mr. Doyle Lewis, at Independence Air Park, on 9 June, 2002.

NTSB Probable Cause

The partial loss of engine power in maneuvering flight due to the rotation of the ignition distributor as a result of a failure to tighten the distributor positioning clamp after the last engine timing adjustment. Factors include an inadequate maintenance activity, no suitable landing terrain below the location where the loss of power occurred, and power lines along the emergency descent flight path.