Mothballing
Portable Dry Air Protection of RAF Interceptors
The Royal Air Force (RAF) uses a highly modified version of the McDonnell Douglas Phantom F4 for both defense interception as well as low-level attack and reconnaissance missions. With more than 70 such aircraft in service around the world, those deployed to the South Atlantic found a general increase in the level of corrosion, specifically to engine, radar and avionics.

To combat these problems, a dry air method of dehumidification was developed for selective application directly to key components of the aircraft. For delivery, it was determined that the equipment requirement was for a robust, compact and simple to operate unit, with dry air hose connections that were uncomplicated, quick to use and required no physical modification of the aircraft.

A simple two-wheeled towable trolley dehumidifier unit was chosen, with storage space for hoses and fittings that connected to the two aircraft engines, radome/avionics and cockpit area to provide approximately 17.5scfm of dry air to each area. Disconnection could occur within five minutes per aircraft and humidity levels were constantly monitored to an RH level of less than 35% within an hour after activation.

The result was a significant increase in both the Mean Time Between Failures (MTBF) as well as the Mean Time Between Arisings (MTBA), with a reduction in man-hour operating costs of approximately 27% for first line fault arisings. Complete return on investment was projected to occur within an impressive five months of implementation and resulted in a formal recommendation to extend system use to the entire fleet of Phantom aircraft.