Tail Trouble

When Bureau of Air Commerce experts convened to investigate Northwest Airlines' crash in which ten were killed near Bozeman, Mont, last month, they may well have had misgivings. For the apparent cause of the accident was major structural failure, a great rarity on airliners. And to the acute discomfiture of the investigating board, their own Bureau of Air Commerce had "rigidly tested" and approved the ship (a new Lockheed 14H which had flown only 190 hours) shortly before the crash.

Last week the board--three B. A. C. men headed by Miller C. Foster of the Department of Commerce, and Montana Aeronautics Commissioner Fred B. Sheriff --issued a preliminary report. Northwest's veteran pilot, Nick Mamer, was completely exonerated. Helpless at the controls after part of the tail structure of his plane "fluttered" off, Pilot Mamer could do nothing but await death as his ship plunged to the ground.

The twin tail of the Lockheed 14H--resembling from the rear a letter H with two vertical tail fins and rudders attached to a wide horizontal stabilizer--is designed to increase controllability and stability in flight. Savoia-Marchetti, Sikorsky. Consolidated, Handley Page. Mitsubishi all have models with similar twin tails. Knowing that if "flutter"--vibration so violent that it shakes metal like a piece of cloth --developed anywhere it would be in the tail structure, Lockheed engineers and Chief Test Pilot Marshall Headle worked for months to eliminate the possibility, finally satisfied themselves and the B. A. C. that they had.

Not so satisfied was Royal Dutch Airlines (K. L. M.). which in ordering eleven new Lockheeds insisted on a better aerodynamic balance in the twin tail--and got it. Lockheed, proud of its $100,000, 250-m.p.h. ship, is now adding a static balance similar to that on K. L. M.'s to all 14H models. Only eight of this model have so far been delivered (all to Northwest Airlines) but the 5 1/2-acre Lockheed plant at Burbank, Calif., just enlarged after a record year's business ($4,750,000), has more than $6,000,000 in unfilled orders.

Meanwhile, the seven remaining Lockheed 14Hs that belong to Northwest Airlines have been corrected in the airlines' St. Paul shops. Nonetheless, B. A. C. last week suddenly cracked down, suspended for 15 days Northwest's license to carry passengers because of failure to maintain equipment up to required standards. This was a slap in the face for Northwest Airlines, which until this crash due to a structural failure, had the enviable record of eleven years' flying over difficult mountain terrain without one fatal accident.

Croil Hunter, president of Northwest Airlines, promptly called at the Department of Commerce. Considering Northwest's record as prima facie evidence of careful operation, observers regarded the suspension of Northwest's passenger license -- not only for its Lockheed 14Hs but for all its ships--as punitive. They guessed that the Department of Commerce, up to its ears in criticism for having approved the fatal ship, would quickly restore Northwest's license, look for another goat. Said Senator Copeland, accident-conscious chairman of the Senate Commerce Committee: "Whether or not the structure of the plane was properly planned is the question and the embarrassing thing is that the plane was approved by the Department."

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