Accident at Gage, Oklahoma, 15 Jun 1954 (N-3007C)

Accident narrative

On June 15, 1954, a Great Lakes Airlines Douglas (N 3007C) made an emergency landing off the runway at the Gage, Oklahoma, airport due to an uncontrollable engine fire. The aircraft was destroyed by fire, but all 75 passengers, four infants, and three crew members evacuated without injury.

**The flight** Flight 146 originated in New York with a destination of Burbank, California. Following a routine crew change and refueling in Kansas City, Missouri, the aircraft departed at 0107 on June 15. Takeoff weight was within allowable limits. Captain Charles F. Pedesky and First Officer Frank J. MacDonald, Jr., were at the controls, with Stewardess June E. Miller in the cabin.

**The emergency** At 0305, while flying near Gage, the flight was cleared to climb to 6,000 feet. Radio reception in the area was poor due to static from local thunderstorms. Shortly after the climb began, the stewardess entered the cockpit to report sparks trailing from the number 3 engine. The first officer checked from his window but saw nothing unusual, and the captain found the engine instruments indicating normally. The stewardess was told to return to the cabin and advise if she saw anything else out of the ordinary.

At approximately 0308, at an altitude of 5,500 feet, the zone 2 fire warning light for the number 3 engine came on. The first officer checked the cabin and confirmed the engine was on fire. The captain leveled the aircraft, feathered the number 3 propeller, pulled the firewall shutoff valve, and discharged the first bank of carbon dioxide. When the fire did not go out, he closed the cowl flaps and discharged the second bank of CO2. The fire died down momentarily before flaring up again.

At 0312, the first officer radioed Gage Interstate Airways Communications (INSAC) to advise that the engine was on fire and the propeller feathered. The Gage communicator turned on the north-south runway lights.

Unable to extinguish the fire, the captain began a descending left turn toward the Gage airport. During this turn, the number 3 engine fell from the aircraft, resulting in a complete failure of the electrical system. Without landing lights or further radio contact, and unable to see the runway lights, the captain headed toward the airport beacon. The first officer used a flashlight to read the altimeter and airspeed indicator. As the aircraft neared the ground, the fire illuminated the surface, allowing the captain to land safely.

The aircraft touched down off the runway. After rolling approximately 1,100 feet, the fire-damaged right main landing gear collapsed, and the aircraft skidded sideways to a stop. The captain ordered an immediate evacuation, which was accomplished in an estimated one and a half minutes.

**What the investigation found** The number 3 engine was recovered 11 miles northwest of the airport. Investigators found that the inner and outer races of the generator's front bearing were badly galled and distorted. The generator drive shaft was broken, but its shear section—designed to fail under excessive loads—remained intact. Rotational score marks on the armature indicated it was still turning when damaged.

The aircraft's electrical system had been modified by the carrier from four 100-ampere generators to a two-generator system, with 300-ampere generators mounted on engines 2 and 3. The number 3 generator had accumulated 550 flight hours since an overhaul that included replacing the front bearing.

The Board concluded that the initial malfunction was the failure of the generator bearing. Because the drive shaft failed to shear at its designed section, the bearing failure generated extreme frictional heat. This heat weakened and burned through adjacent fluid lines, releasing flammable fluids that ignited. The resulting fire progressed too rapidly for the available CO2 to extinguish it.

The Board noted that the complete loss of electrical power when the engine separated was most probably caused by a ground fault on the power cables. The off-runway landing occurred because the surface runway lights were obscured by tall grass, making them invisible from a low approach unless an aircraft was directly lined up with the runway.

The Gage INSAC communicator stated he did not hear the flight report a fire, only a feathered propeller, which the Board considered probable due to radio static. Unaware of the landing, the communicator did not notify the local volunteer fire department until the crew walked into his office.

The Board commended the crew for effecting a safe night landing without aircraft lights and for the prompt, efficient evacuation of all passengers.

**Probable cause** The Board determined that the probable cause of this accident was "a bearing failure of the number 3 engine generator causing extreme frictional heat and the release of inflammable fluid which ignited in flight."