Hot air to save air force millions

An aviation version of a domestic dehumidifier could save the air force millions of dollars in maintenance.

Unforeseen corrosion in the engines on the air force's two Boeing 757 VIP passenger transport aircraft has caused the air force embarrassing breakdowns, one while flying Prime Minister Helen Clark to the South Pacific Forum last year.

Air force spokeswoman, Squadron Leader Sue Connolly, said one of the twin-engined aircraft was now back in service after maintenance in America last week.

The other was likely to be out of action in a hangar at Whenuapai in Auckland until the end of next month when a refurbished engine could be fitted.

The engine problem was found to be corrosion caused by the low flying hours demanded of the aircraft, resulting in them sitting in humid conditions in Auckland.

The air force bought only one spare engine with the two aircraft in 2003 but three of the five engines were found to be damaged.

The problem was not known to other Boeing 757 operators who placed a high demand on their engines meaning they ran hot most of the time, avoiding corrosion, said

Sqn Ldr Connolly said the air force and Rolls Royce, who made the engines, decided on new service protocols to keep the engines dry when they were not running.

These included engine covers when the aircraft were on the ground in Auckland and a dehumidifier to pump warm, dry air through the engines to keep out damaging moist air.

She said the engine problems were not anticipated when the aircraft were bought.

"We put them down to the utilisation rate and the atmospheric conditions in Auckland. We should not have this problem again. It was highly unusual."

- NZPA