Forced Landing of Piper Navajo in Northern Ontario Following Engine Failure

Casualties unknown • Pickle Lake, Ontario, 30 nm E, CA

A single-engine forced landing in a swampy area near Pickle Lake was caused by a mechanical failure in the aircraft's left magneto.

What happened

On a flight from Pickle Lake to Kashechewan, Ontario, a Piper PA 31-310 Navajo, registration C-FWQX, experienced engine issues while cruising at 9500 feet. The pilot first noted a rumble from the left engine accompanied by dropping temperatures. After reversing course toward Pickle Lake, the left engine's performance worsened, leading the pilot to shut it down to prevent catastrophic failure.

As the aircraft continued toward Pickle Lake, the pilot encountered moderate turbulence and a loss of airspeed. Despite attempts to maintain altitude by adjusting power and airspeed, the aircraft began a steady descent. The pilot eventually executed a forced landing in a lightly treed, swampy area approximately 30 nautical miles east of Pickle Lake. The landing resulted in two minor injuries and substantial damage to the aircraft, including damage to both wings and the horizontal stabilizers, though no fire occurred.

The investigation

Investigators examined the left engine, propeller, and magneto. They discovered that the left magneto's distributor block bushing had become loose, causing the distributor rotor to lose synchronization with the engine. This mechanical failure caused the engine to run rough and backfire.

Technical reviews also focused on the pilot's response and the aircraft's maintenance history. While the aircraft had been maintained according to regulatory requirements, investigators looked into whether specific service bulletin recommendations had been followed. The investigation also assessed the pilot's familiarity with the aircraft's handling characteristics during single-engine operations and the adequacy of the procedures outlined in the Pilot Operating Handbook (POH).

Findings

  • The left magneto distributor rotor gear teeth uncoupled from the input pinion gear, causing the left engine to lose power and run improperly.
  • The pilot shut down the left engine but did not immediately increase power on the remaining engine, leading to a decrease in airspeed and difficulty maintaining directional control in turbulence.
  • The gradual loss of altitude necessitated the forced landing.
  • Using the engine securing procedure as a standalone instruction carries a risk that a pilot may not apply enough power to the operative engine to maintain flight.
  • Failure to follow the 500-hour magneto inspection recommended in Service Bulletin 643B may allow a loose distributor block bushing to go undetected.

Probable cause

The primary cause of the engine failure was the mechanical failure of the left magneto due to a loose distributor block bushing. The subsequent inability to maintain altitude was contributed to by the pilot's failure to immediately adjust power on the operating engine and the lack of specific power setting guidance in the aircraft's engine shutdown procedures.

Frequently asked questions

What happened in the 2010-09-10 Piper PA 31-310 Navajo, C-FWQX accident near Pickle Lake, Ontario, 30 nm E, CA?

A single-engine forced landing in a swampy area near Pickle Lake was caused by a mechanical failure in the aircraft's left magneto.

What aircraft was involved and where did it happen?

The accident on 2010-09-10 involved a Piper PA 31-310 Navajo, C-FWQX, operated by Northern Waterworks Sales and Consulting Inc., at Pickle Lake, Ontario, 30 nm E, CA.

What was the probable cause of the accident?

The primary cause of the engine failure was the mechanical failure of the left magneto due to a loose distributor block bushing. The subsequent inability to maintain altitude was contributed to by the pilot's failure to immediately adjust power on the operating engine and the lack of specific power setting guidance…

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