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The impressive growth of naval air power cannot be explained simply in terms of the number of first-line fighting planes which contributed so effectively to the surrender of the enemy. The factors that made this air power such a potent instrument for war can be listed ad infinitum. Such a listing, however, would not in itself tell the whole story. Building air strength was one thing; keeping it powerful was quite another. Once created, naval air power had to be continuously maintained.
A combat aircraft is considerably more than a flying mechanism. It must be equipped with such things as guns, bombs, navigational devices, special instruments, cameras. It requires fuel, lubricants, and painstaking mechanical checks, not only to keep it flying, but to keep it in fighting trim. The relative importance of these factors to the ultimate fighting performance of the aircraft can hardly be exaggerated. Without any item of equipment the possibility of combat inefficiency or downright failure is evident. Without proper and adequate maintenance the best military aircraft in the world would soon become as useless as a rusty shotgun on a wall.
No plane can fly long without upkeep. Combat aircraft require even more specialized upkeep or maintenance than types engaged in routine operational flying. Not only must normal engine overhaul be attended to but battle damage repaired. These planes had to be restored to fighting condition, serviced and rearmed by speedy and efficient maintenance crews, and returned to action in a minimum of time.
The standard naval aircraft radial engine is a complex unit of over 14,000 parts. That it must not fail in flight is the obvious axiom on which maintenance is focused. It can function only within specified time limits before it requires routine overhauls. The longer it flies, the more intensive and extensive becomes the necessary maintenance until after 500 to 600 flying hours or •approximately 90,000 flying miles it must be p354 completely disassembled and rebuilt or even replaced altogether. It is an obvious but important fact that an airplane is not like an automobile that can be pulled over to the side of the road for minor repairs by the driver; nor is it like a ship whose power plant can be maintained while under way. Even though emergency repairs can sometimes be made in the air, the airplane must return to its base, carrier, or tender for proper service and maintenance by a highly skilled crew of properly equipped specialists.
In the days before the war, maintenance was a relatively simple matter when confined to well-equipped naval air stations with permanent facilities and established sources of materials, personnel, power, communications, and transportation. Major overhaul and assembly were performed customarily by large assembly and repair (A&R) shops located at permanent air stations in the United States or in territories owned or leased by this government. Routine maintenance, short of major overhauls or structural repairs or changes done by these A&R shops, was usually performed by each pilot for his own plane, with the help of a small ground crew that traveled with the squadron for this purpose.
The exigencies of combat made this old system as obsolete as many of the aircraft it maintained. A war fought over such vast distances in so many parts of the world required that maintenance function where aircraft were in combat. Furthermore, the complexities and number of new types of aircraft which were constantly being developed meant that maintenance personnel had to be not only experts in aircraft types but specialists as well in aircraft component parts.
In the early part of the war it was necessary to return aircraft engines to Hawaii or the United States for major overhauls, a process which kept each engine out of action for approximately six months. As the war progressed into the southwest Pacific and then northward into the Philippines, this problem was rapidly overcome by the establishment of large semi-permanent A&R shops together with supply depots of aircraft parts on island bases. These shops were not more than a day's flying time from combat areas, and overhauled engines were never out of action for more than twenty‑one days. It was estimated that A&R facilities built in three months at Noumea, New Caledonia, saved the Navy and our allies over $12,000,000 in investment for new engines and by serving army, navy, marine, Australian, and New Zealand aircraft of all types, made immediately available •some 45,000,000 additional flying miles.
The Integrated Aeronautic Program, an outgrowth of the recommendations made by a board headed by Rear Admiral (later Vice p355 Admiral) Arthur Radford and charged with developing an Integrated Aeronautic Maintenance, Material and Supply Program, in 1944 relegated all major overhaul and repair to the continental United States and provided for replacements of completely new aircraft rather than the return of renovated aircraft to combat areas. Thus the entire maintenance problem was greatly lessened, because new aircraft which required a minimum of operational maintenance were always on hand. Service units thereafter devoted their efforts to routine maintenance and repair of battle damage rather than to fighting normal wear from hard use.
The most significant departure from traditional maintenance procedures were the new policy of keeping maintenance crews permanently attached to a ship or shore station instead of accompanying squadrons as they alternated between ships or shore establishments for training or combat duties. Even before December 7, 1941 it was recognized that in the event of war, shore establishments would be required to perform a larger volume of maintenance, leaving carriers and tenders as free as possible of routine upkeep in order to concentrate their efforts on the kind of maintenance that kept a maximum number of planes constantly ready to fly. But as the first trickle of naval aircraft into combat areas swelled into an unprecedented flow, it became obvious that existing maintenance organizations were antiquated and that the need for an entirely new system was acute. This problem was resolved by the creation of several kinds of naval aircraft service units designed to meet the over‑all maintenance requirements of naval aircraft of all types and especially "tailored" to support specific models.
The common denominator of all these service units was that they were completely integrated mobile organizations trained to maintain naval aircraft from ship or shore bases anywhere in the world. Like any other naval vessel or activity, each service unit was usually organized into several divisions; engineering, flight operations, ordnance, communications or electronics, first lieutenant, supply and disbursing, personnel, and medical. Under each division were the various departments and shops which performed the actual maintenance work on aircraft. There was usually a shop for each type of upkeep and repair: machine, metal, hydraulic, instrument, electronics devices, carpenter, paint, propeller, photo, CO‑2 and oxygen, procure rigging, instrument, tire. Because these service units were created for the sole purpose of aircraft maintenance they were relieved for the most part of any additional duties not strictly related to support of their own personnel and the aircraft assigned to their care. For that reason these units seldom operated independently. p356 They were always based on a naval air facility in the United States or its territories or upon advance base units in forward areas. At advanced bases these service units usually operated with an ACORN, the Navy's term for an organization of men and equipment designated to construct rapidly and operate an air base or to repair and operate a captured enemy airfield. In effect, the ACORN built and operated a forward-area naval air station on which the service units maintained aircraft.
In those few cases where major repairs were performed in combat areas, Aircraft Repair and Overhaul units, AROU's in naval parlance, handled the job. Such units operated from our bases at Noumea, Guadalcanal, and Espiritu Santo. By far the most numerous and versatile of these units, however, were the Carrier Aircraft Service units, commonly called CASU's. A few weeks after the Japanese attack on Pearl Harbor the first four CASU's were commissioned began to operate in the Hawaiian area. Because CASU's maintained most types of combat aircraft including fighters, fighter-bombers, torpedo planes, dive bombers, and night fighters in the later phase of the war, they were redesignated Combat Aircraft Service units, or CASU (F)'s (the [F] indicated Forward Area). During some of the Pacific island campaigns they supported marine, army and Allied combat aircraft as well as their regular navy charges. While all CASU's were theoretically stamped from the same mold, much of their value stemmed from their flexibility. Those units which operated in combat zones concentrated their efforts on keeping their squadrons in the air, while CASU's based in the United States or Hawaii assumed the added responsibilities of receiving new planes, training personnel in their duties and commissioning men and planes as squadrons. This function of the CASU's operating from permanent naval air stations was especially important because they were responsible for organizing and training the service units that maintained aircraft aboard aircraft carriers, the Carrier Aircraft Service divisions, or CASD's. Quite often experienced CASU personnel became the nuclei for new CASD's in process of formation.
Scout Observation Service units, or SOSU's, were similarly created to service scout observation planes which operated from battleships, cruisers and, in a few instances, from destroyers. Patrol Service units, PatSU's, were established to maintain patrol aircraft, usually the large land-based Liberators or Venturas as well as the "Cats," Catalina flying boats. PatSU's were usually part of the Headquarters Squadron (HedRon) of a fleet air wing. Since all these service units were basically the same in p357 organization and function, with suitable training a CASU could be redesignated a PatSU, or a SOSU could become a CASU to meet the requirements of changing squadron types under their care.
Lighter-than‑air (LTA or blimp) maintenance was generally organized along similar patterns, Blimp HedRon's were usually responsible for airship maintenance which differed little in most cases from that required by airplanes, except for specialized problems such as fabric damage and helium control. Major repairs and engine overhauls were normally performed at permanent air facilities in the United States, while interim checks and minor repairs were effected at advance LTA bases in the South Atlantic and Caribbean areas.
Aside from that performed aboard carriers, aircraft maintenance afloat was confined primarily to two types of vessels, aircraft tenders and aircraft repair ships. Aircraft tenders were well-known ships of the train long before the outbreak of war. Equipped with complete facilities for maintaining all types of seaplanes, they operated as floating bases for as many as twenty aircraft and their crews at a time. On occasion they served to transport air groups and aviation supplies in addition to their normal maintenance duties. They were attached to fleet air wings and often served in the Atlantic and Pacific as flag ships of fleet air wing commanders. Aircraft repair ships converted from both Liberty ships and LST's were developed during the war to supplement shore-based maintenance units. They were completely equipped with the same kind of shops and facilities as shore-based units and provided emergency aircraft maintenance offshore until a beachhead was secured and the CASU was in full operation. During this period their work was largely limited to maintaining component parts of aircraft brought from the beach in small boats.
The Japanese publicly attribute their defeat to American scientific skill and mechanical "know‑how." It was a combination of these two factors, especially under the severest combat conditions, that kept our naval aircraft, sometimes inferior in performance and oftentimes inferior in numbers in the early phases of the war, at the peak of fighting efficiency until our superiority in all categories was overwhelmingly and permanently established.
Improvisation was a keynote throughout all the American armed forces. Seldom did it show up so markedly as in the aircraft service units which moved with the fleet and operated from our successive "steppingstone" advance bases. This American "know‑how" produced remarkable results in operational maintenance of naval aircraft. One of p358 the first and perhaps most famous is the story of how a few Marines at Wake Island in the first days of the war kept their pitifully few planes flying against the enemy by determination and ingenuity in patching, repairing and "cannibalizing" parts of one damaged plane to keep another in the air. Even if not against such hopeless and overwhelming odds as those faced by the Wake garrison, this same story of keeping planes in condition to strike the enemy was repeated many times over as naval aircraft spearheaded and then supported the difficult assaults and landings of combined American and Allied forces from Guadalcanal to Okinawa. In the early phases of each of these campaigns, while a beachhead was being secured and before adequate facilities were built, aircraft maintenance units were invariably hard pressed to keep the first planes operating from captured bases in flyable fighting condition. Usually there were planes awaiting battle-damage repairs, refueling, and rearming as soon as the maintenance units arrived. Wrecked or damaged planes not worth repairing served as a steady source of supply for replacement parts for other aircraft until such time as regular maintenance supplies were brought in. Many naval aircraft served important combat duties as "victims" of such "cannibalism."
Maintenance cannot function without materials and supply. It was evident in the very nature of many landing operations that during the initial phases maintenance supplies might be inadequate. The immense quantity of supplies needed for simple maintenance precluded its total arrival on the beachhead simultaneously with the service units. By improvisation and cannibalism plus actual fabrication of needed parts, maintenance units managed to keep planes operational until a normal supply flow was established. Even then these units sometimes continued to improvise, for aside from expected parts and structure failures, battle damage demanded the greatest amount of replacement spares and no matter how carefully anticipated, battle damage could on occasion exceed available supplies of parts. Planes were often forced to jettison valuable and scarce equipment, thus placing unusually large demands on supply. Complete sets of radio, radar, and ordnance gear were "ditched" on occasion to insure a plane's safe return to its base. While such items were always replaced by supply, there were many instances in both the Atlantic and Pacific war theaters in which the Army Air Forces provided badly needed maintenance supplies in the interim. Similarly, the Navy supplied maintenance services and parts to the Army, Marines, and Allied aircraft when requested. In some of these instances the appearance of obsolete or unfamiliar aircraft types for which supplies p359 were not immediately available challenged but never defeated the ingenuity of maintenance and supply men.
Almost everywhere in the world normal problems of aircraft maintenance were complicated by enemy action, geography, and the elements. In addition to regular maintenance instruction, service units in the Pacific were trained in Commando tactics and jungle warfare as well as foxhole and slit-trench "architecture." Some had many opportunities to use such training. CASU (F) 17 went ashore with the Marines on Tarawa, "a square mile of hell," on November 24, 1943, four days after the first landings and immediately began to maintain aircraft on the captured Japanese airstrip on Betio Island. Since this landing was the first American attempt to take a small, low‑lying coral island, there was no definite precedent to follow in planning operations. A CASU was not supposed to carry its own tools and equipment but to rely upon its supporting ACORN for them. Nevertheless it was realized that in the confusion of landing it might be impossible to locate urgently needed crated equipment among the tons of supplies put ashore. It was the CASU's primary duty to service planes immediately to insure a continuous Combat Air Patrol (CAP) over the newly won beachhead. Therefore, each man in the first landing wave was given basic maintenance hand tools to carry in with him. This was probably the first time any CASU went ashore with every possible piece of equipment lashed to gasoline and oil tanks, and to every other available mobile unit. These vehicles served not only to carry equipment ashore but as markers indicating its location.
CASU (F) 17 personnel demonstrated their resourcefulness as improvisers in using captured enemy equipment. Tents, walls of damaged Japanese buildings, scrap lumber, packing cases, and salvaged tin were used to build shops. For four weeks a reconditioned Japanese generator was the only means for charging aircraft batteries and the only available transportation was an abandoned enemy sedan. Even Japanese medical supplies provided valuable ointments for treating lip blisters and infected sores. Old Jap airfield revetments were used as sheltering working spaces and captured .30
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