MIA99LA234
MIA99LA234

On August 23, 1999, about 1226 eastern daylight time, a Bellanca 17-30A, N42VB, registered to N42VB Flying Club, collided with trees during a descent for a forced landing near Robbins, Tennessee. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot, the sole occupant, sustained serious injuries. The flight originated about 1131, from the Tri-Cities Regional TN/VA Airport, Bristol, Tennessee.

The pilot stated that during cruise flight at 6,500 feet mean sea level, while in contact with the Atlanta Air Route Traffic Control Center (ARTCC), he noticed a "slight rate of descent" then checked the engine instruments; all looked well. The cockpit then filled with smoke and the propeller stopped rotating. He declared a Mayday and the controller advised him of a nearby airport. Unable to land there, he initiated a descent for a forced landing in a field. While descending to land in the field, the airplane collided with the tops of trees. The next thing he recalled was exiting the airplane. He later reported that he secured the ignition and master switches, and the fuel selector.

According to a transcription of communications, at 1220:33, the pilot declared a Mayday and 3 seconds later, he advised the controller that "...the engine has stopped." The controller advised the pilot that an airport was located at his 3 o'clock position and 10 miles, and at 1221:13, the pilot advised the controller that, "I don't think I'm gonna be able to make it I'm at uh five thousand now." The controller acknowledge this and at 1222:04, the pilot of another airplane on the same frequency offered assistance to the controller which was utilized as a radio relay between the accident airplane and the Atlanta ARTCC controller. At 1226:15, the pilot of the assisting airplane advised the controller that the accident pilot advised him 1 minute earlier that his landing gear was down and the airplane was on final approach. At 1233:47, the pilot of the assisting airplane advised the controller that he spotted the airplane on the ground and continued to assist by circling over the accident site area to alert rescue vehicles of the location. About 1325:18, the wreckage was reached by the rescuers.

Examination of the accident site by FAA personnel revealed that the airplane came to rest on a west-northwesterly heading about 10 yards from the edge of thick woods. The engine and instrument panel were nearly separated from the airframe; the landing gear was damaged. Visual examination of the exterior of the engine revealed two holes in the crankcase; one of the holes was above the No. 2 cylinder and the second hole was located above the No. 4 cylinder. Five quarts of oil was noted in the oil sump. The engine was recovered for further examination.

Initial examination of the engine in the presence of the FAA inspector revealed that the connecting rods for cylinder Nos. 2 and 4 were broken. The accessory gears and housing were intact; ferrous particles were found in the engine oil pump housing area and in the oil screen. Further disassembly of the engine was performed by the NTSB. External visual examination of the engine revealed sealant type material along nearly the entire length of both crankcase halves on the upper portion of the engine (See photographs 3 and 4). Particles; some being ferrous, were located in the oil screen housing (See photograph 2). Disassembly of the engine revealed that the connecting rod for the No. 1 cylinder was also broken. Fretting was noted at the upper support boss of the No. 2 main bearing; pieces of the No. 2 main bearing were in place but the bearing was broken (See photographs 5 and 6). Brown discoloration was noted at the No. 2 main bearing journal and heat distress was noted at the connecting rod journals of the crankshaft at cylinder Nos. 1, 2, and 4. Damage to the bearing saddle on both crankcase halves of the No. 2 main bearing was noted (See photographs 7 and 8). Connecting rod bearing extrusion was noted at cylinder Nos. 3, 5, and 6. The crankshaft and camshaft were not failed and all fuel injector nozzles were clear of obstructions.

By design, oil is supplied to the Nos. 2 and 3 cylinder connecting rod bearings from the No. 2 main bearing. Additionally, the thru bolt which is adjacent to the fretted area of the upper support boss for the No. 2 main bearing, is used to secure in part the Nos. 2 and 3 cylinders.

According to the Desk Edition of the Metals Handbook, fretting by definition is, "A type of wear that occurs between tight-fitting surfaces subjected to cyclic relative motion of extremely small amplitude. Usually, fretting is accompanied by corrosion, especially of the very fine wear debris. Also referred to as fretting corrosion...."

Review of the airplane maintenance records revealed that the engine received a major overhaul on December 17, 1985, and was installed in the airplane following overhaul on April 15, 1986. An entry dated January 1994, indicates, "...removed and replaced # 3 and # 6 cylinders with yellow tag cylinders. Sealed top of engine case...." The engine had accumulated approximately 995 hours since major overhaul and 328 hours since installation of the Nos. 3 and 6 cylinders respectively, at the time of failure. Further review of the maintenance records indicates that the time between the oil changes at the July 1996 and September 1997 annual inspections was approximately 110 hours. Also, entries in the engine logbook dated June 20, 1998, and July 20, 1998, indicate that the engine oil was changed but the entry does not indicate that the oil screen was checked. The airplane had accumulated 25 hours between these dates. The engine oil was last recorded as being changed on November 6, 1998, at the last annual inspection. The airplane had accumulated approximately 65 hours since then at the time of the accident.

Review of Continental Aircraft Engine Service Bulletin M87-12, dated July 15, 1987, the subject being recommended fuel and oil grades, revealed that, "The recommended oil change interval without full flow oil filters is every 25 hours of operation depending on dust, humidity and engine condition, or every six months, whichever comes first." Review of Teledyne Industries, Inc., Overhaul Manual for the IO-520 Series Aircraft Engine Manual revealed, "Nuts on both ends of thru bolts must be torqued."

The airplane wreckage was released to Mr. Chad Rundell, Regional Claims Manager for Universal Loss Management, Inc., on May 2, 2000.

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