GENERAL INFORMATION FOR NTSB REPORT: ANC00LA035
Data Source NTSB AVIATION ACCIDENT/INCIDENT DATABASE
NTSB Report Nbr ANC00LA035
Event Id 20001212X20577
Local Date 03/10/2000
Local Time 945
State AK
Airport Name DELTA JUNCTION
Event Type ACCIDENT
Injury Severity MINOR
Record Status
Mid Air Collision NO
Event Location OFF AIRPORT/AIRSTRIP

WEATHER INFORMATION
Weather Briefing Complete UNKNOWN
Basic Weather Conditions VISUAL METEOROLOGICAL COND
Light Condition DAY
Cloud Condition CLEAR
Cloud Height above Ground Level (ft) 0
Ceiling Height above Ground Level (ft) 0
Cloud Type NONE
Visibility RVR (ft) 0
Visibility RVV (sm) 0
Visibility (sm) 10
Wind Direction (deg) 70
Wind Condition Flag U
Wind Speed (knots) 7
Wind Condition Indicated Unknown

AIRCRAFT INFORMATION
Aircraft 1
Type of Operation PART 135: AIR TAXI & COMMUTER
Registration Number N75703
Aircraft Make CESSNA
Aircraft Model 207
Aircraft Series UNDESIGNATED SERIES
Aircraft Damage SUBSTANTIAL
Aircraft Fire NONE
Aircraft Explosion NONE
Aircraft Type AIRPLANE
Aircraft Homebuilt UNKNOWN
Phase of Flight UNDEFINED
Aircraft Use UNKNOWN
Category of Operation NON-SCHEDULED
Flight Plan Filed VFR
Domestic/International DOMESTIC
Passenger/Cargo CARGO
Operator Name 40 MILE AIR LTD
Operator Doing Business As
Owner Name LEIF WILSON
Number of Seats 6
Number of Engines 1
ELT Installed YES
ELT Operated YES
Departure Airport Id FAI
Departure City FAIRBANKS
Departure State ALASKA
Last Departure Point NO
Destination Airport Id
Destination City HEALY LAKE
Destination State ALASKA
Runway Id 0
Air Carrier Operating Certificates YES
Air Carrier Other Operating Certificates UNKNOWN
Rotocraft/Agriculture Operating Certificate UNKNOWN
Cert Max Gross Wgt 3800

ENGINE INFORMATION

Aircraft 1 - Engine : #1
Engine Manufactuer Continental
Engine Model IO-520
Engine Horsepower 300
Engine Thrust HP
Carb/Injection FUEL INJECTED

INJURY INFORMATION
Injury Summary for Aircraft 1
Fatal Serious Minor None
Crew 0 0 0 0
Pass 0 0 0 0
Total 0 0 1 0
Sequence of Events for Aircraft 1
Occurrence #1
LOSS OF ENGINE POWER (TOTAL) - MECH FAILURE/MALF
Phase of Operation: CRUISE

Events Sequence for Occurrence #1 of Aircraft 1
Event Seq # Event Group Code Subject Modifier Personnel Cause/Factor
1 1 ENGINE ASSEMBLY, PISTON DISINTEGRATED CAUSE
2 1 IGNITION SYSTEM, SPARK PLUG FOULED FACTOR

Occurrence #2
IN FLIGHT COLLISION WITH OBJECT
Phase of Operation: EMERGENCY DESCENT/LANDING

Events Sequence for Occurrence #2 of Aircraft 1
Event Seq # Event Group Code Subject Modifier Personnel Cause/Factor
3 1 OBJECT TREE(S)




AIRCRAFT 1 PRELIMINARY REPORT


On March 10, 2000, at 0945 Alaska standard time, a Cessna 207 airplane, N75703, sustained substantial damage during an off airport forced landing about two miles northwest of the Delta Junction Airport, Delta Junction, Alaska. The solo commercial pilot received minor injuries. The airplane was operated by 40 Mile Air Service, Ltd., of Tok, Alaska, under 14 CFR Part 135 as an on-demand cargo flight. The flight departed Fairbanks, Alaska, about 0900 for Healy Lake, Alaska, with 50 pounds of mail. Visual meteorological conditions prevailed at the time of the accident, and a VFR flight plan was filed. The pilot of a second airplane, who was approaching Delta Junction at the time of the accident, told the NTSB investigator-in-charge (IIC) during a telephone interview on March 10, that he overheard the accident pilot transmit a "mayday." He located the distressed airplane while it was still in flight and followed it toward Delta Junction. The witness pilot said he observed thin puffs of white smoke, intermittently coming from the area of the engine exhaust. He said the accident pilot transmitted the engine was losing power, and he was going to attempt to reach the Delta Junction Airport. The witness relayed that the pilot then transmitted the engine had quit, and he was going to land. The witness told the IIC the airplane contacted trees and then cartwheeled into a clearing. He said the pilot got out of the airplane, turned off the Emergency Locator Transmitter (ELT), and was assisted by a nearby homeowner. The accident pilot told the IIC, during a telephone interview on March 13, that while in cruise flight at 5,500 feet msl, he detected engine roughness and a slight power loss, so he diverted toward Delta Junction. About 10 miles northwest of the airport, the engine power began to alternate between idle and half power. The pilot stated that varying magnetos, throttle, mixture, and the electric fuel pump, had no effect. He noted that oil pressure, oil temperature, and cylinder head temperatures all registered in the low end of the green range, which he felt was consistent with low power. When the engine lost all power, he said he pulled the propeller control to the high pitch / low rpm position, and the propeller responded. He said he turned the fuel and electrical power to the airplane off prior to impact. On March 10, two FAA inspectors inspected the airplane at the accident site and observed fuel in both wing tanks, and no preaccident anomalies with the airplane or engine. Initial shop inspection of the engine on March 13 by an FAA airworthiness inspector revealed detonation and disintegration of the number two piston, and metal particles in the induction system and seven spark plugs. The fuel manifold, fuel distributer lines, and fuel nozzles were tested on a calibrated flow bench under supervision of the NTSB IIC on May 8. All components flow tested within manufacturer's tolerances. The magneto to engine timing, internal magneto timing, and ignition harness integrity, was checked on May 12. No anomalies were noted. A review of the engine logbooks revealed that the day prior to the accident flight, the fuel nozzles, and spark plugs, were cleaned. The number two cylinder was replaced on February 12, 1999, at 4,014 tachometer hours, 817 hours prior to the accident. Since that time, the numbers three, four, five, and six cylinders were also replaced, due to stuck rings and burnt exhaust valves. The number one cylinder had been replaced 181 hours prior to the replacement of the number two cylinder. The manufacturer's service bulletin, SB 91-8, recommends a time between overhauls (TBO) for the IO-520 engine of 1,700 hours. The engine had accumulated 1,560 hours since overhaul.

AIRCRAFT 1 FINAL REPORT


The pilot stated that while in cruise at 5,500 feet msl, the engine began to run rough, and slowly lose power. The pilot attempted to reach an airport, but the engine lost total power. The airplane contacted trees and cartwheeled into an open field. Inspection of the engine revealed detonation and disintegration of the number two piston, and metal fouling of seven spark plugs. Bench testing of the fuel and ignition system revealed no discrepancies with the fuel distributor, lines, or nozzles; and no discrepancies with either magneto, magneto timing, or ignition harness. Manufacturer's service bulletin 91-8 recommends a time between overhaul (TBO) for the IO-520 of 1,700 hours. The engine had accumulated 1,560 hours since overhaul. The number two cylinder had been replaced 817 hours prior to the accident. All six cylinders had been replaced at different times within the previous 998 hours.

AIRCRAFT 1 CAUSE REPORT


The disintegration of the number two piston. A factor in this accident was the subsequent metal fouling of the spark plugs, which resulted in total loss of engine power.


END REPORT