GENERAL INFORMATION FOR NTSB REPORT: ANC00IA083
Data Source NTSB AVIATION ACCIDENT/INCIDENT DATABASE
NTSB Report Nbr ANC00IA083
Event Id 20001212X21350
Local Date 07/04/2000
Local Time 1910
State AK
Airport Name DEADHORSE
Event Type INCIDENT
Injury Severity NONE
Record Status
Mid Air Collision NO
Event Location ON AIRPORT/AIRSTRIP

WEATHER INFORMATION
Weather Briefing Complete NOT PERTINENT
Basic Weather Conditions VISUAL METEOROLOGICAL COND
Light Condition DAY
Cloud Condition UNKNOWN
Cloud Height above Ground Level (ft) 0
Ceiling Height above Ground Level (ft) 2000
Cloud Type OVERCAST
Visibility RVR (ft) 0
Visibility RVV (sm) 0
Visibility (sm) 10
Wind Direction (deg) 260
Wind Condition Flag U
Wind Speed (knots) 20
Wind Condition Indicated Unknown

AIRCRAFT INFORMATION
Aircraft 1
Type of Operation PART 135: AIR TAXI & COMMUTER
Registration Number N73100
Aircraft Make CESSNA
Aircraft Model 207
Aircraft Series A
Aircraft Damage MINOR
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 COMPANY VFR
Domestic/International DOMESTIC
Passenger/Cargo CARGO
Operator Name CAPE SMYTHE AIR SERVICE
Operator Doing Business As
Owner Name CAPE SMYTH AIR SERVICE, INC.
Number of Seats 4
Number of Engines 1
ELT Installed YES
ELT Operated NO
Departure Airport Id SCC
Departure City DEADHORSE
Departure State ALASKA
Last Departure Point NO
Destination Airport Id 10AK
Destination City NUIQSUT
Destination State ALASKA
Runway Id 4
Runway Length 6500
Runway Width 150
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-F
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 0 1
Sequence of Events for Aircraft 1
Occurrence #1
AIRFRAME/COMPONENT/SYSTEM FAILURE/MALFUNCTION
Phase of Operation: APPROACH

Events Sequence for Occurrence #1 of Aircraft 1
Event Seq # Event Group Code Subject Modifier Personnel Cause/Factor
1 1 ENGINE ASSEMBLY, CRANKSHAFT FRACTURED CAUSE
2 3 INADEQUATE QUALITY CONTROL MANUFACTURER FACTOR




AIRCRAFT 1 PRELIMINARY REPORT


On July 4, 2000, about 1910 Alaska daylight time, a wheel equipped Cessna 207A airplane, N73100, sustained minor damage during an emergency landing at the Deadhorse Airport, Deadhorse, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand cargo/U.S. mail flight under Title 14, CFR Part 135, when the accident occurred. The airplane was registered to, and operated by, Cape Smyth Air Service, Inc., Barrow, Alaska. The solo certificated airline transport pilot was not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Deadhorse Airport, Deadhorse, about 1900, and was en route to Nuiqsut, Alaska. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on July 10, the pilot reported that about 10 minutes after departure, while in cruise, level flight, he noted a light sheen of oil forming on the windshield, and he elected to return to the Deadhorse Airport. He said that by the time he was within two miles of the airport he was having difficulty seeing though the windshield due to a heavy accumulation of oil. The pilot reported that while on approach to runway 4, the propeller rpm increased for about 20 seconds, followed by the propeller detaching from the engine. He said that he was able to glide the airplane to the runway, and land without further incident. The propeller and engine crankshaft flange were located, and sent to the NTSB metallurgical laboratory for examination. The airplane was equipped with a Teledyne Continental Motors (TCM) IO-520-F engine. The engine had accrued a total time in service of 9.0 hours, and was installed in the incident airplane on July 1, 2000, 3 days before the incident. The engine maintenance records note that the engine was "rebuilt/zero timed on September 15, 1999 by Teledyne Continental Motors in accordance with an FAA approved Quality Control System." Assembly records indicate that a rebuilt crankshaft, serial number A239610N, was installed during the rebuild. A Safety Board metallurgist examined the fractured crankshaft flange, and reported that his initial visual examination revealed that about one half of the fracture was on a flat plane and contained crack arrest positions, features indicative of fatigue cracking. He added that the primary fatigue initiation appeared to be from a very large number of individual initiation sites in the center of the fatigue region. A representative from TCM's in-house analytical laboratory reported that previous crankshaft flange failures of this nature were the direct result of a propeller blade strike during engine operation. However, the operator's director of maintenance reported that no propeller blade strikes occurred with the incident engine within the 9.0 hours of operation, or 3 days, since the incident engine was installed. The representative from TCM's in-house analytical laboratory reported that during a portion of the rebuilding process, the crankshaft is plated with tin that serves as a corrosion inhibitor. He speculated that if a crack were present prior to being rebuilt, tin would be present within the fracture surface. The Safety Board metallurgist that examined the fractured crankshaft flange reported that there was no detectable tin found within the fracture surface. The Safety Board metallurgist added that if a crack was present at the time of the tin application, a preexisting crack might not have been sufficiently open to allow penetration of the tin. The Safety Board released the fractured crankshaft to the operator's director of maintenance on October 11, 2000. The Safety Board retained no other airplane or engine components.

AIRCRAFT 1 FINAL REPORT


The certificated airline transport reported that about 10 minutes after departure, while in cruise, level flight, he noted a light sheen of oil forming on the windshield, and he elected to return to his departure airport. He noted that by the time he was within two miles of the airport he was having difficulty seeing though the windshield due to a heavy accumulation of oil. He said that while on approach to the airport, the propeller rpm increased for about 20 seconds, followed by the propeller detaching from the engine. He said that he was able to glide the airplane to the runway, and land without further incident. A postincident investigation revealed that the engine had been rebuilt/zero-timed by Teledyne Continental Motors, 9.0 hours of operation, and 3 days before the incident. A Safety Board metallurgist examined the fractured crankshaft flange, and reported that his initial visual examination revealed that about one-half of the fracture was on a flat plane and contained crack arrest positions, features indicative of fatigue cracking. He added that the primary fatigue initiation appeared to be from a very large number of individual initiation sites in the center of the fatigue region.

AIRCRAFT 1 CAUSE REPORT


An in-flight fracture of the engine crankshaft propeller flange. A factor associated with the accident was the manufacturer's inadequate quality control standards.


END REPORT