Accident Curtiss C-46F-1-CU Commando N5075N,
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ASN Wikibase Occurrence # 336367
 

Date:Tuesday 19 July 1949
Time:21:01
Type:Silhouette image of generic C46 model; specific model in this crash may look slightly different    
Curtiss C-46F-1-CU Commando
Owner/operator:Air Transport Associates
Registration: N5075N
MSN: 22463
Year of manufacture:1945
Total airframe hrs:255 hours
Engine model:Pratt & Whitney R-2800-75
Fatalities:Fatalities: 2 / Occupants: 32
Other fatalities:1
Aircraft damage: Destroyed, written off
Category:Accident
Location:Seattle-Boeing Field International Airport, WA (BFI) -   United States of America
Phase: Take off
Nature:Passenger - Non-Scheduled/charter/Air Taxi
Departure airport:Seattle-Boeing Field International Airport, WA (BFI/KBFI)
Destination airport:Chicago (unknown airport), IL
Investigating agency: CAB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The Air Transport Associates flight taxied from the loading ramp at Boeing Field at 20:43. The crew taxied the aircraft to the south end of runway 31, where they parked for a period of 13 minutes to accomplish the before takeoff check list. The engines and other components of the aircraft appeared to operate normally, so at 20:58, after receiving clearance from the tower, takeoff was started. Fuel selector valves for both engines had been positioned to the front tanks which contained 91 octane gasoline. Wind was from the northeast at six miles per hour, and visibility was eight miles, under a ceiling of 8,500 feet. Power was advanced to 45 inches of manifold pressure and to 2,700 RPMs for takeoff. The aircraft rolled approximately 3,500 feet down the runway, then became airborne at an air speed of 105 miles per hour. During the takeoff run one of the engines was heard to sputter and backfire, and an unusual amount of torching or exhaust flame was observed coming from both of the engines. Because the left engine did not seem to be developing full power, the Captain, at an altitude of about 20 feet, retarded the throttles, and the aircraft settled back to the runway. At the time of the accident the runway length had been reduced by 1,700 feet to 5,800 feet. The captain after touching down on the runway, approximately 4,500 feet from the start of the takeoff and 1,300 feet from the green threshold lights, did not believe that he had sufficient runway remaining to accomplish a safe stop, so he advanced the throttles to the limit of 52 inches. Both engines responded, but the left continued to misfire. After a momentary ground roll the aircraft again became airborne at an air speed of 105 miles per hour. The landing gear was retracted, airspeed increased slowly to approximately 110 mph, and the flight passed over the north end of the runway at about 50 feet above the ground in a nose high attitude. Sufficient altitude could not be obtained to fly over power lines and poles to the north of the airport, and 1,500 feet north of runway 31 the aircraft struck a 56-foot pole two feet below its top. The impact tore away six feet of the right horizontal stabilizer and elevator. A second pole, 1,480 feet from the first, was struck, then a third pole 200 feet from the second. As a result of striking these poles airspeed and altitude were lost, and 200 feet from the third pole the aircraft crashed into a three-story frame house. The aircraft carried away the entire top story of this structure, then it plunged into and demolished a single-story brick dwelling. The aircraft came to rest on the foundation of the brick dwelling in an upright position.

PROBABLE CAUSE: "The indecision of the pilot in continuing a takeoff after loss of power in the left engine, which loss was probably caused by the use of 91 octane fuel, necessitating the operation of the aircraft's engines in excess of the approved limitations."

Accident investigation:
cover
  
Investigating agency: CAB
Report number: final report
Status: Investigation completed
Duration:
Download report: Final report

Sources:

CAB File No: 1-0056

Location

Revision history:

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