What happened
On October 15, the aircraft N909 and 43, a Lockheed L-188 Electra, departed Honolulu as the final leg of an around-the-world itinerary. The flight was destined for San Francisco via various Pacific stops. While cruising at 21,000 feet, the number one engine experienced an overspeed event. The crew attempted to reduce power and use flaps to manage airspeed, but they were unable to feather the propeller on the malfunctioning engine. To manage the situation, the captain cut off the oil supply to freeze the engine, but the propeller subsequently decoupled and continued to windmill.
As the aircraft descended, the crew noted that the number four engine was only producing partial power. The flight crew contacted a U.S. Coast Guard weather station, known as "November," to request assistance for a potential water landing. After calculating that remaining fuel was insufficient to reach San Francisco or return to Honolulu, the crew decided to orbit the cutter while awaiting daylight. During this period, the number four engine suffered a backfire and lost power entirely, though its propeller was successfully feathered.
At 0540, the captain notified the USS Pontchartrain of the intent to ditch. Following the deployment of a foam path by the cutter, the aircraft performed a controlled ditching at 0615. All 24 passengers and crew successfully evacuated into liferafts without any fatalities. The aircraft sank shortly after the evacuation was completed.
Findings
- An initial mechanical failure prevented the feathering of the number one propeller.
- A secondary mechanical failure led to a total loss of power from the number four engine.
- The decoupling of the number one propeller during the attempt to freeze the engine caused it to windmill, necessitating airspeed restrictions to prevent further overspeeding.