Engine loses power on takeoff

Aircraft: Piper Twin Comanche. Injuries: 1 Serious Location: Big Bear City, Calif. Aircraft damage: Substantial.

What reportedly happened: The airplane had recently undergone maintenance, which included the overhaul of both engines. The pilot flew the Comanche into the airport the day before the accident and, after landing, called the maintenance facility to report that the right engine was running rough. A mechanic was not available to help him. The owner of the maintenance shop told the pilot not to fly the airplane until a mechanic could check out the engine. The owner of the shop did not heard from the pilot again.

The next day the pilot took off in the Comanche. He reported that after takeoff, as he turned onto the left crosswind leg of the traffic pattern, the right engine lost power. He continued to turn onto the downwind leg, making sure to keep the airspeed above the single-engine control speed of 90 mph. His last recollection was turning to final approach and seeing the runway.

A witness in the area reported hearing the sound of an engine popping and backfiring before the airplane started the takeoff roll. The airplane crashed into a home located about 900 feet from the runway threshold. An ear-witnesses to the accident reported that the engine was popping and backfiring during the takeoff roll.

The post-accident examination of both the right and left engines revealed no evidence of mechanical failures or malfunctions that would have precluded normal operation. Based on information recovered from a GPS unit on the aircraft, it was determined that the airplane continued to climb on the downwind leg to pattern altitude and then descended and reduced power to final approach. The last heading was aligned with the runway with a ground speed of 76 mph and 1,400 feet east of the landing threshold. Investigators determined that the pilot likely allowed the airspeed to decrease below the single-engine control speed and did not maintain sufficient altitude to clear the house while on final approach.

Probable cause: The pilot’s failure to maintain the minimum single-engine control speed while on final approach for landing. Contributing to the accident was the pilot’s decision to fly with a known deficiency in one engine and a loss of power in that engine for reasons that could not be determined because post-accident examination did not reveal any mechanical failures or malfunctions that would have precluded normal operation.

NTSB Identification: WPR11LA113

This January 2011 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

Comments

  1. ROBERT BURNS says:

    he found no problem with the engines because my guess is the only problem was that the two red knobs were all the way forward. big bear is almost 7,000 ft elevation at that altitude the fuel injected engines on a Twin co will be way rich with full mixture and will pop and crack as reported.

  2. Dennis Reiley says:

    Two witnesses reported popping and backfiring from the plane and the investigation doesn’t find anything wrong. Not only does the pilot fly a known unsafe aircraft but the crash investigator can’t find an engine problem when it is known to have one. Sounds like two peas from the same pod.

  3. Why why why are we continuing to not engage the brain before the throttle! Known deficiency……..what more do you need to know to make a “no-go” decision??? We are killing ourselves and GA by continuing these actions. Simply ask the question “am I airworthy? (yourself and the aircraft). Is the answer no? Then dont fly, period.

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