Accident Curtiss C-46D-10-CU Commando N74689,

ASN Wikibase Occurrence # 335786

Date:	Sunday 16 September 1951
Time:	10:47
Type:	Curtiss C-46D-10-CU Commando
Owner/operator:	Peninsular Air Transport
Registration:	N74689
MSN:	32975
Year of manufacture:	1944
Total airframe hrs:	5754 hours
Engine model:	Pratt & Whitney R-2800-75
Fatalities:	Fatalities: 0 / Occupants: 53
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Chicago-Midway Airport, IL (MDW) - United States of America
Phase:	Initial climb
Nature:	Passenger - Scheduled
Departure airport:	Chicago-Midway Airport, IL (MDW/KMDW)
Destination airport:	Covington-Greater Cincinnati Airport, KY (CVG/KCVG)
Investigating agency:	CAB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The day before the accident the aircraft was flown from Miami, Florida, to Chicago, with stops at St. Petersburg and Covington. On the leg between Covington and Chicago, malfunctioning of the left engine was experienced. This trouble manifested itself by intermittent misfiring, and was corrected by the use of full-rich mixture. At Chicago the aircraft was refueled late in the evening of the same day, September 15, and maintenance work on the left engine was performed by Butler aviation personnel on the following morning. The flight was to be over the reverse route and with the same stops as had been made on the previous day. The aircraft was cleared to take off on runway 31L. According to the weight and balance manifest, the takeoff weight was the maximum allowable (45,000 pounds). However, in fact the authorized gross weight was exceeded by approximately 1,960 pounds. The C-46 became airborne at a speed of about 100 or 105 mph, and simultaneously the left engine started misfiring. The landing gear was raised. Then the left engine started backfiring. The captain placed the left mixture control in the full-rich position. The did not stop the misfiring, and he then turned off the left engine's right magneto. The engine continued to fire erratically, the captain put the magneto switch back on both magnetos, the engine then lost all power, and its propeller was feathered. The aircraft started a slight turn to the left. The aircraft climbed slowly on its right engine to an attitude estimated at from 150 to 200 feet. The aircraft continued to turn gradually to the left and altitude was being lost. Ahead the captain saw a sizable stretch of open land and decided to crash land. He cut the power on the right engine, nosed the aircraft down, quickly flared it out, and landed exceptionally hard with landing gear and flaps retracted. The severity of contact broke both engines completely free of their mounts. The aircraft rode over both engines, bounced several times and slid to a stop.

PROBABLE CAUSE: "The Board determines that the probable cause of this accident was the poor technique used by the pilot in taking off at too low an air speed to maintain single engine flight, followed by a critical loss of power from the left engine, and subsequently a partial loss of power from the right engine, conditions which were aggravated by the effects of the overload."

Accident investigation: