It was the seventh deadly U.S. cargo crash involving MU-2s since 2000 -- second only to the Cessna 208B.

An earlier crash, in icy weather in Idaho Feb. 11, 2000, raises further questions about FAA oversight -- and the NTSB's rulings.

That crash killed a 67-year-old pilot flying a plane operated by American Check Transport.

The pilot had retired from a major airline before flying cargo and had more than 21,000 hours of flight time on his résumé. But that morning he reported a dual engine flameout. Just seconds later he crashed into a ridgeline a mile and a half from the runway at Lewiston Nez-Perce County Airport.

The NTSB said the pilot failed to follow the flight manual procedures "resulting in both engines flaming out when the air induction system was blocked with ice."

As a contributing cause, the safety board said the company industry service bulletin that "strongly recommends" operators install an auto-ignition system meant to avoid the precise problem encountered that morning in Idaho, reducing the possibility of engine flameout during icing. In fact, in 1995, Mitsubishi had issued a bulletin urging its installation.

But it wasn't until five years later that the FAA formally required it -- three months after the Idaho crash.

After the series of fatalities, U.S. Sens. John F. Kerry and Edward M. Kennedy and U.S. Rep. Barney Frank, all of Massachusetts, cited Lennon's BWI crash last September in urging FAA Administrator Marion C. Blakey to review "whether the MU-2 has a place in the safest aerospace system of the world."

"The MU-2 has a disturbing statistical record in terms of safety," they wrote on behalf of the pilot's sister, a Massachusetts resident. "No more Americans should have to die piloting an MU-2 while the FAA fails to provide at least an outline of a safety review."

From 1983-2005, 45 MU-2s fatally crashed in the United States, killing 120 people in cargo and other crashes, records show.

The Mitsubishi has spoilers instead of ailerons, the small hinged sections of the wing that help control the plane's bank. Some think this feature can make the plane hard to handle in times of stress, a point the company disputes.

"It is especially important for airmen who do not fly the MU-2 exclusively to be aware that performance expectations and control techniques common in other turboprop twins do not necessarily transfer to flying the MU-2," FAA Flight Standards Service Director James J. Ballough wrote.

"The MU-2 has always been looked at as something of a hot rod in terms of small turboprop aircraft," said FAA spokesman Les Dorr. "That said, if you rely on your training and rely on your procedures in the manual, you should be able to fly the aircraft without a problem. ... That is not to say we won't order changes."

In fact, a new FAA report said the MU-2's accident rate is twice as high, and its fatality rate 2.5 times higher than similar twin turboprops designed in the same era -- contradicting earlier claims.