CHI00LA292

The airplane impacted terrain following an application of engine power by the pilot so as to extend his touchdown point due to a waterline traversing the approach end of the grass runway. During the application of power, the engine hesitated and backfired while the airplane was in a near stall phase of flight 3-8 feet above the grass runway. Following the momentary hesitation, the engine accelerated, and the airplane entered a left banked turn, which resulted in the left wing contacting the ground. A functional test of the engine's fuel servo indicated that it exceeded its upper service flow limits. An obstruction of the servo's diaphragm with diaphragm material was found. When the obstruction was removed, the fuel servo was within service flow limits during a second functional test. Scoring of the idle metering plates was also noted.

On September 8, 2000, at 1650 central daylight time, a Cessna 182S, N182KC, owned and piloted by a private pilot, was substantially damaged on impact with terrain during an aborted landing on runway 16 (3,050 feet by 80 feet, grass) at the Eagle Field Airport (0MU0), Ellington, Missouri. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot reported minor injuries, and the three passengers reported no injuries. The flight departed the Rodgers Municipal-Carter Field Airport, Rodgers, Missouri, at 1510, en route to 0MU0.

During a postaccident telephone interview, the pilot reported that he was set up for a perfect soft field landing when he flew over the approach end or the runway at a speed of 75 knots. He stated that he was 3-4 feet agl and "a little short" when he was attempting to avoid a "water line' which extended across the approach end of the runway. He advanced the throttle and the engine "hiccupped". He advanced the throttle an additional amount, applied right rudder and at that time the engine "backfired". At this point, the airplane was heading towards the left side of the runway and a fence. The airplane flew over the fence and then impacted terrain.

The pilot reported, "While making final approach over runway approximately 6 to 8 ft. above ground at full landing configuration -full flaps, stall warning started to sound. I made a decision to make a soft field landing. As I went forward with the throttle to extend my point of landing, the engine started to hesitate. I glanced down to see if I had fuel flow and did a quick glance of my instruments. I gave the engine more throttle thinking it was going to accept it, but the engine continued to flutter and with P factor, I turned into a quick left bank turn and increased my stall configuration. I then heard a loud sound like a backfire and lost power - at that point I was heading into a fence. In the stall configuration with no power, my left wing was down. The airplane hit the ground with the nose hitting ground."

"I feel that if the engine would not have taken a large amount of fuel at once, I could have had right rudder and continued having power. I would have extended my landing or made a decision to go around..."

The 1997 Cessna 182S, serial number 18280049, was powered by a Lycoming IO-540-AB1A5 engine, serial number L-26076-48A. An annual inspection of the engine was entered in the engine logbook on November 15, 1999 at a total time in service of 257.2 hours. The engine accumulated a total time in service of 442.9 hours.

The engine was removed from the airframe and shipped to Textron Lycoming for an engine examination and engine run. The spin-on oil filter and suction screen did not contain any visible particles. The top spark plugs were dark in color and free of deposits. The following engine components were replaced due to impact damage resulting from the accident: both cylinder number five shroud tubes and exhaust push rod, and cylinder number six intake and exhaust push rods and housing. A slave servo unit was used in place of the accident airplane's fuel injection servo during post accident engine testing. A borescope inspection of the cylinder indicated no abnormalities. The top spark plugs and ignition leads were reinstalled. The engine was then placed on a test stand and run for approximately 5 minutes. For the following 30 minutes, the engine speed was varied from idle, to 1,200 rpm, to 2,200 rpm, and back to idle. An engine speed hesitation and backfiring was noted when the throttle was advanced quickly from an idle speed to a cruise speed with the mixture control partially pulled out. The throttle was retarded and advanced again, but the hesitation and backfiring was not duplicated.

A functional test of the engine's Precision Airmotive fuel injection servo (Model RSA-5AD1, serial number 70135106) was performed under the supervision of an engineer from the Federal Aviation Administration's Wichita Aircraft Certification Office. The rate of fuel flow during the functional test exceeded the upper service flow limits for two of the four test points. Disassembly of the servo's regulator revealed the presence of aluminum pieces in both the metered and unmetered fuel chambers. These pieces appeared to be from the inlet port's threads. A non-metallic material was also found lodged in the regulator seat. The disassembly also noted that the idle metering plates were scored. The regulator was cleaned and the fuel servo reassembled with a replacement idle lever assembly for another functional test, which resulted in all test points falling within the fuel servo's service flow limits.

The Cessna Aircraft Company performed an Attenuated Total Reflectance-Fourier Transform-Infra Red Spectroscopy analysis of the non-metallic material; the results indicated that the material was of the same composition with that of the fuel servo's diaphragm.

Parties to the investigation were the FAA, Cessna Aircraft Company, and Textron Lycoming.