ASN Aircraft accident Martin 2-0-2 NC93044 Winona, WI
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Status:Accident investigation report completed and information captured
Date:Sunday 29 August 1948
Time:17:05
Type:Silhouette image of generic m202 model; specific model in this crash may look slightly different
Martin 2-0-2
Operator:Northwest Airlines
Registration: NC93044
MSN: 9165
First flight: 1947
Total airframe hrs:1321
Engines: 2 Pratt & Whitney R-2800-CA18
Crew:Fatalities: 4 / Occupants: 4
Passengers:Fatalities: 33 / Occupants: 33
Total:Fatalities: 37 / Occupants: 37
Aircraft damage: Damaged beyond repair
Location:6,6 km (4.1 mls) NW of Winona, WI (   United States of America)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Chicago (unknown airport), IL, United States of America
Destination airport:Minneapolis-St. Paul International Airport, MN (MSP/KMSP), United States of America
Flightnumber: 421
Narrative:
Northwest Airlines' Flight 421 departed from Chicago for Minneapolis at 15:50. At 16:55 the flight reported over La Crosse, 125 miles southeast of Minneapolis, and was at that time cleared to start an en route descent from its cruising altitude of 8,000 feet. Four minutes later the flight reported passing through the 7,000-foot altitude level. The flight proceeded in the direction of Winona where it encountered a thunderstorm. Flight 421 was seen flying below the overcast. As it passed over Winona, the aircraft appeared to enter the roll cloud or the leading edge of the thunderstorm at which time it was lost from view. Seconds later parts of the airplane were observed falling. It was later found that the flight had crashed approximately 4 miles northwest of Winona on a bluff on the east side of the Mississippi River.

Probable Cause:

PROBABLE CAUSE: "The loss of the outer panel of the left wing which separated from the aircraft as a result of a fatigue crack in the left front outer panel attachment fitting which had been induced by a faulty design of that fitting, the fatigue crack having been aggravated by severe turbulence encountered in the thunderstorm."

Accident investigation:

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

Classification:
Thunderstorm
Wing failure
Loss of control

Sources:
» CAB File No. 1-0117


Follow-up / safety actions
Several hours after the accident, fatigue cracks similar to those found in NC93044 were found in the wing root fittings of another Martin 2-0-2, NC93042. This airplane had flown through the same storm area about an hour after the accident. A complete separation had occurred in the front spar lower flange of the right wing of NC93042 at a point corresponding to the initial failure which was found in the left wing of NC93044. Two days after the accident, three other Martin 2-0-2 aircraft, upon inspection, were found to contain fatigue cracks in similar locations to those found in NC93044 and NC93042.

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This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Martin 2-0-2

  • 43 built
  • The first loss
  • The first fatal accident
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 United States of America
  • 6th worst accident (at the time)
  • 92nd worst accident (currently)
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