KENAI, AK, USA
N4839S
PIPER PA-32-260
THE AIRPLANE WAS ON A PART 135 ON-DEMAND AIR TAXI FLIGHT, WHEN PHYSICAL SEPARATION OF THE NO. 3 CYLINDER AND PISTON OCCURRED AND AN IN-FLIGHT FIRE ENSUED. SUBSEQUENTLY, THE AIRPLANE CRASH LANDED ON TERRAIN NEAR THE SHORELINE OF A BODY OF WATER. ONE OF THE FOUR OCCUPANTS SURVIVED THE CRASH, BUT THE SURVIVING PASSENGER COULD NOT RECALL EVENTS THAT LED TO THE ACCIDENT. MAINTENANCE RECORDS INDICATED THAT THE #3 AND #4 CYLINDER ASSEMBLIES WERE INSTALLED ABOUT 220 FLIGHT HOURS BEFORE THE ACCIDENT. THIS MAINTENANCE WAS PERFORMED WITHOUT REMOVING THE ENGINE FROM THE AIRPLANE. NO PROBLEM WITH THE AIRFRAME OR ENGINE WAS RECORDED SUBSEQUENT TO THE CYLINDER CHANGE. INSPECTION OF THE ENGINE REVEALED FATIGUE CRACKS IN THE CASE UNDER THE NO. 3 CYLINDER. MAGNIFIED INSPECTION OF THE CASE REVEALED WEAR AND DEFORMATION DAMAGE, WHERE THE HOLDING FLANGE AND INNER SKIRT OF THE CYLINDER WOULD NORMALLY BE POSITIONED, WHICH WAS CONSISTENT WITH THE CYLINDER MOVING IN RELATION TO THE CASE. ALSO, MECHANICAL DAMAGE WAS EVIDENT ON THE THREADS OF THE STUDS AND BOTH THROUGH-BOLTS.
HISTORY OF FLIGHT On August 14, 1994, at approximately 0927 Alaska daylight time (ADT), a wheel equipped Piper PA-32-260 Cherokee Six airplane, registration No. 4839S, owned and operated by Lake Clark Air, Inc., of Port Alsworth, Alaska, collided with terrain near the mouth of Lake Clark Pass, about 40 nautical miles northwest of Kenai, Alaska. The site of the accident is in the Big River Lakes region. The airline transport certificated pilot-in-command and two passengers received fatal injuries and the remaining passenger sustained serious injuries. The airplane was destroyed. At the time of the accident, the flight was being operated under the on-demand rules of 14 Code of Federal Regulation (CFR) Part 135. The flight last departed the Merrill Field Airport in Anchorage, Alaska at about 0808 on the morning of the fourteenth on a company visual flight rules (VFR) flight plan. The intended destination was Port Alsworth, Alaska, located about 140 miles to the southwest. Visual meteorological conditions prevailed at the time of the mishap. An emergency locator transmitter (ELT) signal associated with the crash site was initially picked up by civilian search aircraft at 1008. The crash site was located at about 1200 ADT. COMMUNICATION INFORMATION The pilot did not report any problems with the airplane, either prior to or during the en route portion of the accident flight. METEOROLOGICAL INFORMATION The Kenai Automated Flight Service Station 1046 ADT Record Observation for Big River Lakes, Alaska on August 14, 1994, was clear, visibility 70 miles, temperature 63F, dewpoint 50F, wind 150@4, altimeter 30.10Hg. PASSENGER/WITNESS INFORMATION The surviving passenger sustained serious injuries in the accident and has no recall of the events leading up to or immediately after the mishap. Aside from the surviving passenger, there were no additional witnesses to the accident. FLIGHTCREW INFORMATION The pilot was the holder of Airline Transport Pilot Certificate No. 2102759, with the ratings of airplane multi-engine land, and commercial privileges for airplane single engine land and sea, and multi-engine sea, latest issue date May 02, 1994. He also possessed flight and ground instructor certificates. His most recent flight medical examination occurred on June 30, 1994, at which time he was issued a 2nd Class Medical Certificate with the limitation that he possess corrective glasses for near vision. He completed his most recent 14 CFR Part 135 proficiency check on July 13, 1994. At the time of the accident, Mr. Reynolds had accrued a total flight time of 12,500 hours of which 500 hours were in the Cherokee Six aircraft. His total flight time and (time in the Cherokee Six) follows: last 90 days 300 hours (25 hours), last 30 days 100 hours (10 hours), last 24 hours 6.9 hours (0.6 hours). MEDICAL AND PATHOLOGICAL INFORMATION The autopsy on the pilot was performed by the Alaska State Medical Examiner, Doctor Michael T. Propst. The forensic toxicology was performed by the Federal Aviation Administration's Toxicology and Accident Research Laboratory in Oklahoma City, Oklahoma. Toxicological testing on the pilot were negative. AIRCRAFT INFORMATION The airplane, a Piper PA-32-260 Cherokee Six, having registration number N4839S, and serial number 32-1268, was manufactured in 1969 by the Piper Aircraft Corporation. At the time of the accident, the airframe had accrued 4702.5 hours. The airframe received its most recent 100 hour inspection on August 6, 1994, at which time it was found to be in airworthy condition. POWERPLANT INFORMATION The airplane was powered by an Avco Lycoming Corporation normally aspirated horizontally opposed reciprocating engine, model O-540-E4B5, serial number L-6329-48C, with a power rating of 260 horsepower. The engine was installed on N4839S on February 10, 1993, at which time the engine had accrued 319 hours since major overhaul (SMOH). At the time of the accident, the engine had accrued 4071.7 operating hours since manufacture, 1266.7 hours SMOH, and 23.1 hours since its most recent 100 hour inspection on August 6, 1994, at which time it was found to be in airworthy condition. Factory new No. 3 (SN:5988-2) and No. 4 (SN:5988-1) cylinder assembles were installed with the engine on the airplane on June 11, 1994, 220 hours prior to the accident. The maintenance records did not indicate the reason for the cylinder changes. There was no indication in the maintenance entry concerning the cylinder work performed that any inspection, other than visual, was associated with the work activity. PROPELLER INFORMATION Coupled to the engine was a Hartzell two blade propeller, model HC-C24K-1BF/F8477-2, serial number CH21213. The propeller underwent its most recent inspection on August 6, 1994, at which time it was found to be in airworthy condition. AIRCRAFT FLIGHT LOG REVIEW At the request of the Safety Board's investigator-in-charge (IIC), the airline provided the aircraft flight log record for N4839S covering the period March 17, 1994 to August 11, 1994. The log pages were not numbered sequentially. The only means of identifying any particular log page was by calendar date. The log pages covering the period August 11, 1994 up to the time of the accident were reportedly still in the aircraft flight log on board the airplane and were not recovered. No aircraft discrepancies concerning engine roughness or performance were found in the maintenance log during the aforementioned period. ON SCENE WRECKAGE AND IMPACT INFORMATION Alaska State Trooper (AST) recovery personnel arrived at the scene of the accident at approximately 1700 on the afternoon of the fourteenth. Further damage to aircraft by the AST's included folding the cabin roof back, tearing out the pilot seat, and cutting seat belts. The Safety Board's IIC arrived at the accident site on August 17, 1994 to begin the on scene investigation. The site investigation was delayed by inclement weather and transportation logistics. The wreckage of the white and blue aircraft was located near the mouth of Lake Clark Pass, 40 miles northwest of Kenai, Alaska. The coordinates of the accident site were 60.51.14 north and 152.17.80 west. ON SCENE EXTERIOR OBSERVATIONS The plane was partially submerged on the south side of a waterway, known locally as Big River, and was resting against the river bank. The bank was about six feet in height and was covered on top with a thicket of alder trees. Pieces of wing skin, fiberglass material, a fuel tank, and the left side of the engine cowling were found among the trees. The main structure of the airplane was in the water partially submerged. The left wing and landing gear were separated from the aircraft and were about 75 feet down river adjacent to the bank. The right wing was twisted inverted and the landing gear was still attached. The wing appeared to be still connected to the fuselage. The engine was submerged and could not be examined. The nose gear, minus the tire, was protruding through the forward part of the cabin floor. The upper and lower halves of the right side of the fiberglass engine cowling were burned. The exterior paint along the right side of the airplane was burned, scorched, and discolored, beginning at the engine cowling traversing rearward to the forward portion of the main cabin/cockpit door. ON SCENE INTERIOR OBSERVATIONS The right upper interior portion of the right main door seal was discolored and there were pieces of suet along the right cabin wall and ceiling. The interior side of the main cabin door window on the right side of the airplane was covered with a thin grayish colored film. The cockpit and cabin floor was buckled upward. The engine and flight control panel was not structurally secured to the aircraft structure. The clock was stopped at 0927. The engine throttle control was full forward. The mixture and propeller controls were halfway in their run. The control linkage for the engine and propeller were broken. The circuit breakers for the alternator output field, engine group, nav/com, instrument lights, and DME were open. The airspeed indicator read about one needle width beyond the 250 knot scale. The gauge was intact and the lines to the gauge were broken. The altimeter read 30.30 inches Hg, and 1,160 feet. The gauge was intact and the lines to the gauge were broken. The vertical velocity indicator read minus 1,800 feet. The gauge was intact and the line to the gauge was broken. Tachometer read 4702.51; zero rpm. The gauge was intact and the line to the gauge was broken. The primer was in and locked. The primer to engine connecting line was severed. All engine gauges were indicating at the low end of their scale. The manifold pressure gauge needle was broken. The magneto switch was on the left magneto and the key was broken. The mechanical flap handle was in the full extend position (30 degrees). The aircraft fire extinguisher was not recovered. POST ON SCENE ACTIVITY The main engine and airframe components were recovered at the crash site and were transported to Anchorage, Alaska for further examination. Present during this activity, in addition to the Safety Board's IIC, were representatives of the Federal Aviation Administration, the airline, and the engine manufacture. Both propeller blades were bent rearward near symmetrically and their leading edges were void of gross abrasion. No blade tip curling was evident. Engine valve and gear train continuity were established during partial crankshaft rotation. An examination of the engine revealed that the No. 3 cylinder assembly, piston and piston pin were missing. The pin end of the connecting rod was bent and damaged, but otherwise appeared straight. All of the cylinder studs were accounted for. The top left stud was loose. The second top stud threads were stripped. The third top stud threads were stripped. The fourth top stud threads were stripped. The bottom left stud threads were stripped. The second bottom stud threads were stripped and the stud was bent downward. The third bottom stud was sheared. The fourth bottom stud showed slight thread damage. The remaining cylinders were removed and visually examined and appeared to be in normal, in service condition. Some effort was required to remove the nuts securing the remaining cylinders to the engine case. Both engine case halves had internal damage, particularly around the No. 3 cylinder base. Several tappet bodies were found broken. The crankcase was stamped AJAX 2857, which indicated that at some point in its history it had received a weld repair. Both magnetos were examined and were found to produce spark during hand operation. The fuel pump was visually examined and no physical defects were noted. Blue colored fuel was present in the pump. The carburetor inlet screen was removed and visually examined and found free of contamination. The No. 3 cylinder fuel primer line was severed. The oil suction screen was removed and visually examined. The screen contained several pieces of ferris and non-ferris material. An examination of the oil filter element revealed fine metal contamination, primarily from non-ferris material. The spark plugs were contaminated by submersion in the water, but otherwise showed normal wear. TEST AND RESEARCH The engine case, SN:L-14159-40, match case No. 4146, were forwarded to the Safety Board's Materials Laboratory Division in Washington, D.C. for examination and analysis. The findings of this effort are contained in the attached Metallurgist's Factual Report No. 95-76.
INADEQUATE ENGINE MAINTENANCE AND/OR INSPECTION, AND FATIGUE CRACKING OF THE ENGINE CASE, WHICH RESULTED IN EVENTUAL DAMAGE TO THE #3 CYLINDER STUDS/ENGINE THROUGH-BOLTS, SUBSEQUENT SEPARATION OF THE #3 CYLINDER AND PISTON, AND AN IN-FLIGHT FIRE.
Source: NTSB Aviation Accident Database
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