Sunday, July 12, 2009

The Convair Conversions






In August of 1966, North Central Airlines began converting its 31 Convair 340's/440's to 580 prop-jets. The first converted 580 was received in January of 1967 and was used extensively for pilot training and familiarization. Then, on April 1st, 1967, North Central officially entered the 'jet age' with the Convair 580 joining in passenger service.

The conversions were performed by PACAERO (Pacific Airmotive Corporation) of California, where the piston engines were removed, replaced by the Allison 501-D13 turbine engines along with the famous 'paddle wheel' Aeroproduct 606 propellers. Along with the engine changes came a heightened tail, by one foot, to accommodate for the more powerful engines. Many cockpit changes and additions were made as well, especially a Collins automatic pilot and dual flight directors.

After the conversions were performed, the aircraft were flown back to MSP for 'face lifting,' where new interiors were added along with the new aqua and gold paint scheme. A total conversion would normally take about a month from start to finish.

Of note is just how close Hal Carr and North Central came to buying a conversion with Rolls-Royce engines instead of Allisons. According to Ceiling Unlimited (The Story of North Central Airlines, page 184) The British powered version was called the Convair 640. NCA Maintenance favored the 640 because of the British engine's reputation for reliability, but Flight Operations preferred the more powerful Allisons, and Mr. Carr went along with that recommendation - a wise choice, it developed, because the 640 eventually had to operate under severe restrictions that reduced its usefulness.

The conversion to 580 was so successful, both with passengers and with maintenance and fuel costs, that Mr. Carr expanded conversions to have the entire fleet of Convairs converted to 580 as soon as possible. Of note, shortly after the first 580's began service with North Central, the first DC-9 joined the fleet on September 8th, 1967, beginning the all jet fleet that North Central would rely on for another 12 years before the merger with Southern to form Republic.

I've added a few photos of the conversions taking place at PAC in California, compliments of Steven Pinnow. Aircraft shown are N2046, N90858, N7743U and N4811C. Also added is N4285C, '549', which was the first conversion to 580. Enjoy!

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