Before Pearl Harbor, the military services rated Pratt & Whitney engines at 420 hours between major overhauls. Today 1200-hp Twin Wasps are being flown as much as 975 hours and 2000-hp Double Wasps, 900 hours before being torn down for overhaul which is more than double the prewar figure.
The engines serve longer than the crews before rest. A Consolidated Liberator crew operating over Germany, for example, is relieved usually after logging about 300 hours. Their 1200-hp P & W Twin Wasps, however, may go on to take a second and then a third crew through their tours of duty before the engines are overhauled and returned to action. A fighter pilot would probably be relieved after even fewer combat hours. That means the Double Wasp in a Thunderbolt, Corsair, or Hellcat could serve several pilots before a major overhaul.
That this increased dependability has a most important bearing on commercial airline operation was emphasized by William P Gwinn, Acting General Manager of Pratt & Whitney Division of United Aircraft. Under CAA regulations, domestic airlines in 1941 were permitted to operate their P & W Twin Wasps a maximum of 650 hours between major overhauls. It has now been possible to raise this to 850 hours, which has helped the airlines to handle the swollen volume of traffic with reduced fleets. In Mexico, Cia Mexicana de Aviacion, a part of Pan American Airways System, is regularly flying Twin Wasps for 1,000 hours between major overhauls.
This news clip was originally published in the "Shop Talk" column of the April, 1944, issue of Air Tech magazine, vol 4, no 3, p 72.