Lean mixture results in departure crash

Aircraft: Piper Pawnee Brave. Injuries: None. Location: Cambridge, Neb. Aircraft damage: Substantial.

What reportedly happened: The pilot was departing on the first agricultural application flight of the day. As he was taxiing he noticed the engine temperature rising, so he leaned the mixture.

He completed his engine run-up and took off. As the airplane was accelerating down the runway, he noticed it was not developing enough power, but he had used up most of the runway and could not abort the takeoff.

The airplane lacked sufficient power to climb and crashed in terrain about 600 feet from the airport.

The pilot reported that he inadvertently departed with the engine’s mixture control lever at the halfway leaned setting.

He added that there were no mechanical anomalies with the airplane, and the accident could have been prevented if he had used a checklist.

Probable cause: The pilot’s failure to reset the engine’s mixture control lever to the full rich position prior to takeoff.

NTSB Identification: CEN11CA526

This July 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. Tom says

    I was always told to lean while taxiing to cut down on fouling the plugs, and to lean so much that the engine would sputter if I tried to advance the throttle to more than taxi speeds. Can’t hurt the engine by leaning aggressively at idle, although you might accidentally shut it off.

  2. says

    In my 40+ years of flying, I once forgot to enrich the mixture before takeoff from a low-elevation airport. But once I applied full power, it was immediately obvious that something was wrong. Surely the ag pilot would have noticed the lack of full power before he/she got to the point where an abort was no longer possible, don’t you think?

  3. John says

    Chris,
    No you are correct. The report from the pilot probably said he leaned the mixture to smooth out the engine while running rough in taxi, not hot but….it will sure get hot carrying a hopper full of weight when he took off with the mixture half way out…that is until the engine quit!

    • peter says

      you are correct, that’s why this didn’t make sense…
      with an engine temperature rise you are supposed to rich the mixture and open the cowl flap. as he was taking off reducing power would not be an option until he was at 500 feet AGL.

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