North American TB-25J Mitchell
44-31183      29 January 1946
Will Rogers Field, Oklahoma


Excerpts from the crash report

Assigned 348th AAFBU, Will Rogers Field, Oklahoma

Rank
Name
Position Injury
Lt. Col
Smith, Robert R.
Pilot
Minor
Lt. Col
Beeson, Duane W.
Co-Pilot
None
Sgt.
Shepherd, Raymond D.
Flight Engineer
Major


History of the flight:

The aircraft had been cleared on a local training flight.  The pilot had been checked out in the B-25 within the last three days [ed note: Col. Smith had
774 hours total flight time (153 of them actual combat time) but only 5 hours 50 minutes logged in B-25 aircraft prior to the crash].  The Co-Pilot was not qualified as [B-25] 1st Pilot, and had only two previous flights in that type aircraft [ed note: Col. Beeson had 859:50 hours total time (230 actual combat hours) but only 5 hours 30 minutes logged in B-25 aircraft prior to the crash].  The Engineer had just been placed on flying status although he had done some flying as engineer previously [ed note:  Sgt. Shepherd had been removed from flight status due to a reaction to sulfa drug and had just recently been returned to flying]. 

The engines were started and the aircraft taxied out to Runway 17 for takeoff.  The engines were run up and tested in the usual manner, no malfunctions being noted at the time.  Wing flaps were not used for takeoff.  Power check above thirty-seven inches M.P. [Manifold Pressure] was not made by pilot before taking off.

The takeoff run was made using only 42 inches of manifold pressure.  It was not until the aircraft was airborne and the gear had been retracted that anything abnormal in its performance was noted by either the pilot or co-pilot.

Engine instruments were checked for any abnormal readings.  The instruments checked then do not include the carburetor air temperature gauge, and consequently a reading of that instrument cannot be given at this time. 

As speed and altitude could not be increased the pilot attempted to return to the field by starting an easy turn to the left.  Unable to reach the field,  the condition growing worse, the airplane was landed wheels-up in a pasture.  The aircraft first touched the ground in a nose high attitude, skipped approximately 150 yards and came to rest in the shallow pond shown [in the photograph]. 

Upon examination of the wreckage the carburetor air scoop gates were found closed.  The carburetor air exhaust scoops were found open.  The carburetor air scoop gate control handles were found in the neutral position. 

The crew chief's statement points out that the carburetor air scoop gates were closed and the controls returned to neutral after preflight that morning.  The pilot did not check operation of carburetor air temperature mechanism before takeoff as outlined on checklist.  The pilot did not check the airscoop gate or exhausts visually.  The control handles for carburetor heat were only checked for neutral position.

On the takeoff run it was observed by the tower operator that the aircraft was having trouble.  Abnormal puffs of black smoke were observed.

It is possible that carburetor airscoop gate creeped closed during takeoff due to possible malfunction of the system.  T.O. 01-60GE-27 which provides the correction had not been complied with. 

As no previous creepage had been reported the board discounts the theory that creepage occurred on the flight.

From the above facts, the board concluded the cause of the accident was loss of power in both engines due to the detonation caused by the carburetor airscoop gates being closed. 
 

 

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