WPR14LA315

The commercial pilot reported that, before the first flight leg of the day, he used the engine primer during a cold engine start. He did not use the primer before he departed for the accident flight leg. He stated that, during cruise flight, he began to slowly climb the airplane to cross a ridgeline, and, as he pushed the throttle up, the engine did not respond. He pumped the throttle numerous times, and the engine finally responded; however, the airplane had lost altitude and airspeed, and he was forced to land the airplane in a wooded area. Examination of the wreckage revealed that the spark plugs' electrode areas were dark and sooty, indicative of a rich-mixture condition. The engine primer plunger was found in the unlocked-and-extended position, and it was undamaged and would lock when the lugs were engaged. The primer position and the condition of the spark plugs indicated that the engine power loss was likely due to an overly rich mixture, which resulted from excess fuel being pulled through the primer into the engine's intake system when power was applied. The Starting checklist procedures indicated that, after using the primer, the primer plunger should be locked. An unsecured primer plunger can cause the engine to run richer than normal and result in a rough-running engine, loss of power, and blackened spark plugs. It is likely that, when the pilot used the primer while starting the engine before the first flight leg, he did not ensure that it was locked before initiating the accident flight in accordance with the Starting checklist and that this led to the subsequent in-flight loss of engine power. The calculated density altitude at cruise altitude at the time of the flight was about 9,240 ft, which would have further degraded the engine's performance.

On July 27, 2014, about 1045 Pacific daylight time, an Ercoupe, 415-C, N2013H, sustained substantial damage during a forced landing following a reported loss of engine power during cruise flight near Susanville, California. The commercial pilot and passenger sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The local flight departed Rogers Field Airport (O05), Chester, California, about 0940. A family member of the pilot reported the airplane overdue to local law enforcement on the afternoon of July 27, 2014, after becoming concerned when the pilot had not arrived at his planned destination. The Federal Aviation Administration (FAA) issued an Alert Notification (ALNOT) for the missing airplane. The wreckage was located by law enforcement personnel about 1922 on July 27, 2014, in rugged terrain. In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot stated that during the first flight leg that day, the airplane primer was used during a cold engine start. The next flight was the accident leg, and due to the short period the engine was shutdown, the primer was not used for engine start during this leg. On the accident flight, the pilot stated that while in cruise flight about 6,500 feet mean sea level (msl), he began a slow climb to cross a ridgeline and as he pushed the throttle up, the engine did not respond. He pumped the throttle numerous times and the engine finally responded but the airplane had lost altitude and airspeed and he was forced to land the airplane in a wooded area. Subsequently, the passenger and him egressed and hiked to safety. Utilizing the weather conditions at the nearest reporting station, the density altitude was calculated by the IIC to be about 9,240 feet for the cruise altitude about the time of the accident flight. An examination of the airplane wreckage was conducted by a FAA inspector at the accident site. The airplane's fuselage and wings were observed to have been substantially damaged. All major structural components of the airplane were present in the wreckage. The inspector observed that the engine primer plunger was in the unlocked and extended position. The primer plunger was observed to be undamaged and would appropriately lock when the lugs where engaged. Further, the recently installed spark plugs were removed and observed to be dark in color. No additional anomalies were observed that would preclude normal operation of the engine. The airplane's manual, starting cockpit checklist states to use the primer 2 to 6 strokes and then to lock the primer plunger.