NTSB Factual Report

HISTORY OF FLIGHT

On September 28, 2015, about 1320 Pacific daylight time, a Cessna 150F, N8529G, was substantially damaged following an emergency landing and collision with terrain after a reported loss of engine power during initial climb near Port Townsend, Washington. The commercial pilot and his sole passenger were seriously injured. Visual meteorological conditions prevailed for the personal flight, which was being conducted in accordance with 14 Code of Federal Regulations Part 91, and a flight plan was not filed. The flight departed the Jefferson County International Airport (0S9), Port Townsend, Washington, runway 27, about 1315, with Skagit Regional Airport (BVS), Burlington, Washington, the destination.

In a report submitted to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that shortly after taking off and reaching an altitude about 600 feet above ground level, the engine made a loud "popping" noise and died. The pilot stated that in an attempt to restart the engine he tried priming it, but the engine would not start. The pilot concluded that he had no further memory of what occurred after he attempted to restart the engine.

Three witnesses provided the NTSB IIC with statements relative to their observations of the accident. Their observations revealed the following:

Witness number one reported that he observed the airplane climbing out after taking off, and the engine sounded normal, but shortly thereafter the engine sounded like it was cut, followed by the sound of a backfire; the backfire was after the engine had stopped. The witness stated that he then heard two distinctive crash sounds.

The second witness, who was working at the golf course where the airplane crashed, reported that he heard a small [air]plane having engine trouble, and that while watching it he heard it backfire, and subsequently the engine "went dead.". The witness stated that about 2 minutes later he heard what sounded like a crash.

A third witness, who was on the 17th hole of the golf course, opined that he observed a small [air]plane fly low overhead, and thought it was trying to land on the fairway, as it was listing to the left. The witness stated that he did not hear any engine noise when the airplane flew over, and seconds later heard a loud crash. The witness reported that upon arrival at the site of the accident, gas was spewing from the damaged left wing. Additionally, both occupants were conscious, and the pilot commented that he did not know what had happened.

The airplane was located within a stand of trees about 20 ft north of the aft tee box for the 17th hole at the Discovery Bay Golf Course, Port Townsend. The airplane had sustained impact damage to both wings, the engine and propeller, and the cabin/cockpit areas as a result of the collision with trees. The accident site was about 1.15 nautical miles northwest of the departure end of 0S9's runway 27.

The airplane was recovered to a secured storage facility for further examination.

PERSONNEL INFORMATION

The pilot, age 69, possessed a commercial pilot certificate with single-engine land, multiengine land, single-engine sea, and instrument airplane ratings. The pilot reported a total flying time of 3,000 hours, with 2,000 hours in the same make and model as the accident airplane, and 20 hours of multiengine time. Additionally, the pilot reported that in the last 90 days and 30 days, he had flown 20 hours and 1 hour respectively. The pilot's most recent flight review was conducted on September 8, 2014. The pilot received his third-class Federal Aviation Administration airman medical certificate on August 11, 2015, with the stated limitation, "Must have available glasses for near vision."

AIRCRAFT INFORMATION

The accident airplane was a Cessna model 150F, serial number 15062629. It was a two-place, single-engine, high-wing airplane, with a fixed tricycle landing gear configuration. The airplane was powered by a 100-horsepower Continental Motors O-200-A engine, serial number 62418-5-A. The airplane was originally issued a utility category, standard airworthiness certificate in December, 1965.

Maintenance records revealed that the most recent annual inspection was completed on January 9, 2015, at a calculated airframe total time of 2,383.4 hours, and a recorded tachometer time of 51.4 hours. Records also revealed that the airplane's engine was overhauled at a tachometer time of 49.0 hours. However, the logbook entry for the installation does not specify a date; just above the logbook entry, a date of 9-5-13 was handwritten, as well as a written tachometer time of 28.0, and a handwritten total time of 2,332.0 hours. The pilot reported that the engine had accumulated a total of 41.4 hours since the overhaul.

It was revealed during a postaccident investigation of the airplane's engine that four crankshaft gear bolts had sheared, and that the accompanying gear's dowel pin had failed due to a fatigue fracture. In an interview with the airframe and powerplant mechanic who had performed the engine overhaul, when questioned by the NTSB IIC if he possessed a calibrated torque wrench, he said that he did, and that he had used the tool during the overhaul. When queried as to which overhaul manual he used, the mechanic stated that he used the Continental O-200 Overhaul Manual, which was dated January 1984.

The mechanic revealed to the NTSB IIC during the interview that he felt that the crankshaft gear bolts had failed as a result of a sudden engine stoppage when the airplane collided head-on with a tree. As such, the failure of the crankshaft gear bolts was not the cause of the accident, however, was as a result of the accident. The mechanic further opined that he felt there was nothing wrong with the engine, and that what probably precipitated the loss of engine power was carburetor ice. He added that the accident pilot told him earlier that morning that he had to wait about 30 minutes or so for the fog to lift so he could take off.

METEOROLOGICAL INFORMATION

At 1315, the weather reporting facility at the Oak Harbor Airport (OKH), Oak Harbor, Washington, located about 14 nm northeast of the accident site, reported wind 340° at 8 knots, visibility 10 miles, sky clear, temperature 17°C, dew point 9°C, and an altimeter setting of 30.05 inches of mercury.

According to the carburetor icing-probability chart, for the area conditions reported at about the time of the accident, moderate icing could be expected at cruise power, and serious icing conditions might be expected at descent power.

WRECKAGE AND IMPACT INFORMATION

A survey of the accident site revealed that the airplane's wings had impacted trees on a heading of north at the 40-foot level. This was followed by the propeller/engine colliding head-on with a 28-inch diameter tree in the same direction, and at the same height. The airplane then rotated about 90 degrees to the left prior to falling vertically to the ground, where it came to rest upright in a densely tree and bush covered area. The forward section of the airplane and both wings were substantially damaged, while the aft fuselage and empennage sustained only minor damage. There was no postcrash fire. All components necessary for flight were accounted for at the accident site.

On October 15, 2015, under the supervision of the NTSB IIC and a Federal Aviation Administration aviation safety inspector/airworthiness, and with technical support provided by field representatives for Continental Motors Inc. and Textron Aviation, an examination of the engine and airframe was performed. The results of the examinations revealed the following:

Airframe

The right wing remained attached to the fuselage at all attach points, with the outboard one-third of the wing substantially damaged due to impact forces with trees. The wing strut remained in place, and was not damaged. The right flap remained attached to the wing's trailing edge at all attach points, and was observed impact damaged. The right aileron remained attached to the wing's trailing edge at all attach points, and was not damaged. The wing's fuel tank was intact, with the fuel cap observed in place and tight to touch.

The left wing remained attached to the fuselage at all attach points. The outboard two-thirds of the wing was observed to have sustained heavy impact damage and deformation as a result of tree impact forces. The wing strut was not damaged. The inboard one-third of the wing sustained moderate impact damage, with some wrinkling observed. Additionally, the outboard two-thirds of the wing was bent down about 45°. The aileron remained attached to the wing's trailing edge at all attach points, with minimal damage observed. The wing's fuel tank was breached due to impact forces, with the fuel cap observed intact, not damaged, and tight to touch.

The airplane's vertical stabilizer remained attached to the aft upper fuselage area at all attach points, and was not damaged. The rudder remained attached to the trailing edge of the stabilizer at all attach points, and was not damaged. The right horizontal stabilizer remained intact, and attached to the aft fuselage at all attach points. The outboard tip was damaged mid-span. The right elevator was intact, and remained attached to the right stabilizer's trailing edge at all attach points. The outboard tip of the elevator was observed separated. The left horizontal stabilizer, which was not damaged, remained intact, and attached to the aft fuselage at all attach points. The left elevator, which was not damaged, was intact, and remained attached to the right stabilizer's trailing edge at all attach points. The elevator trim tab remained connected to the elevator at all attach points, and observed in the neutral position.

It was confirmed that all of the control cables were properly attached during the review of the wreckage, with control continuity confirmed throughout the airplane. A visual examination of the flap actuator revealed that the flaps were in the UP position. The flap position indicator was observed in a position beyond the FULL UP position.

Fuel samples from the carburetor and the fuel strainer were observed light blue in color, and tested negative for water with water detection paste. The fuel handle was observed in the wreckage in the off position; however, the valve handle had been placed on the OFF position by the first responders. Air was applied to the right wing root fuel line with the wings removed and the fuel valve in the off position. Air was expelled out of the left wing root fuel line. With the fuel selector valve then placed in the ON position and the left wing fuel line held closed, expelled air was confirmed coming from the fuel strainer. The fuel vent line was tested with air, and the vent line was free of obstructions.

The examination revealed no anomalies with the airframe that would have precluded normal operation.

Engine

At the direction of the NTSB IIC, the engine had been removed from the airframe prior to the examination. Additionally, the number three rocker box cover was removed, and all ignition leads were removed from their respective spark plugs. The starter motor was imbedded, and removed from the firewall for safety reasons.

The examination revealed that the engine had remained intact, and displayed impact damage signatures. All four cylinders remained attached to the engine, and displayed varying degrees of impact damage. The crankcase remained intact, and was unremarkable. The two-bladed fixed pitch propeller remained attached to the crankshaft. The propeller blades displayed minor impact damage, with no bending or twisting deformation observed.

Both magnetos remained attached to their mounting pads, and displayed minor impact damage. The ignition harness displayed impact damage signatures, with a few of the ignition leads partially severed. All of the spark plugs remained in their cylinders, and were visually observed to be unremarkable. The carburetor had broken free from the induction system, and displayed damage consistent with impact forces. The induction system displayed damage at the induction manifold in the form of bending.

The right magneto remained attached to its mounting pad, and displayed minor impact damage. The magneto was removed, and the drive shaft rotated by hand. The impulse coupling operated normally with spark produced at all four distributor posts in normal order. There were no anomalies noted with the magneto.

The left magneto remained attached to its mounting pad, and displayed minor impact damage. The magneto was removed, and the drive shaft was rotated by hand; the impulse coupling operated normally. During impulse coupling operation, it was observed that the magneto would produce a spark on all four distributor posts simultaneously. The magneto was retained by the NTSB IIC for further examination.

The ignition harness sustained impact damage; several of the ignition leads for the right magneto were partially severed. The left magneto ignition harness was tested, and it was capable of conducting a spark from the magneto to the ignition lead end. There were no preimpact anomalies noted with the ignition harness.

All spark plugs remained installed in their respective cylinders. The spark plugs were removed, and visually inspected. It was noted that the number two bottom spark plug was oil soaked, which was consistent with postaccident accumulation. It was noted that all electrodes displayed normal operating and wear signatures.

The carburetor had broken free from the induction system, and displayed damage consistent with impact forces. The control arms remained secure to their shafts. The carburetor inlet fuel screen was removed, and observed to be clear of contaminates. The carburetor was disassembled, and the internal components inspected. The floats were intact, and attached to the carburetor and the needle valve. It was noted during float movement that the needle valve would not move, and was in the UP position. When air was blown into the carburetor fuel inlet, no air would pass through the valve. The floats and needle valve were removed; there were no visual anomalies noted with the valve. The valve and floats were then reinstalled and actuated. The valve operated, however, occasionally it would stick in the FULL UP position. After the needle valve was freed, air was blown into the inlet. It was observed that air was capable of passing through the valve. There were no further anomalies noted.

The oil sump displayed impact damage. Subsequent to the sump being removed, a portion of a crankshaft gear bolt and an oil bottle cap were observed in the bottom of the sump.

The oil pick-up tube and screen were undamaged, and clear of contaminates.

The oil pump remained intact, and capable of normal rotation. Subsequent to the pump being disassembled, a few metal flakes were observed in the pump housing. The oil pump gears displayed normal operating signatures. The oil pressure relief valve displayed normal seating and operational signatures.

The engine had an oil filter and adapter installed. The oil filter was removed, and the housing cut open. The filter pleats were inspected, with a minute amount of metallic material observed within the pleats. It was reported that the engine had been overhauled within the last 100 hours.

The original engine oil screen remained installed, despite the fact that the engine was equipped with an oil filter. When the oil screen was removed, a significant amount of contaminates consistent with metallic material as well as a significant amount of unidentified black colored substance was observed.

All four cylinders remained attached to their respective cylinder bays, and were not damaged. It was noted that there was no torque seal on any of the cylinder attachment nuts. Each cylinder was removed, and visually inspected. With the exception of the number two cylinder, it was noted that there was a significant amount of black sealant type material covering the majority of the cylinder flange and skirt; the number two cylinder was void of a black sealant type material. It was also noted that one of the number two cylinder hold down nuts appeared to be a stand

NTSB Probable Cause

The loss of engine power due to the mechanic's inadequate tightening of the crankshaft gear retaining bolts during an engine overhaul, which resulted in fatigue failure of the bolts and the crankshaft gear dowel pin that allowed the crankshaft gear to separate from the crankshaft.