Military


A-10/OA-10 Thunderbolt II

Maintenance

The Thunderbolt II can be serviced and operated from bases with limited facilities near battle areas. Many of the aircraft's parts are interchangeable left and right, including the engines, main landing gear and vertical stabilizers. Design simplicity, ease of access and interchangeable components make the A/OA-10 aircraft readily maintainable and suitable for deployment at advanced bases.

Built around two main criteria, survivability and ease of maintenance, the A-10 is a very well designed aircraft. Large maintenance panels on the sides of the aircraft provide easy access to the A-10's main systems. Since it had a generic airline propulsion system, two General Electric TF-34A's, engine repair and maintenance costs are still relatively inexpensive. In fact, the most expensive repair on the A-10 is a new paint job.

It is now very difficult to get some replacement parts for the A-10. Most of the subcontractors who built parts for it have since gone out of business--and discarded the design blueprints to their parts. In fact, the Air Force often has to re-design, re-tool and re-manufacture its own A-10 parts when the original systems fail. The A-10 has been retro-fitted with a heads-up-display (HUD) that occasionally requires repair.

The A-10 fleet suffers from main Attitude Direction Indicator (ADI) problems with reported failures including off flags, jittery behavior, and bank and pitch errors, all of which remain failed or return to normal operation. The ADI is being replaced. Unfortunately, the field was late identifying that the ADI needed replacement; when pilots started reporting the malfunctions in numbers great enough to flag a problem, the time delay to procure and install a suitable substitute took the USAF more time. Relying on available trustworthy instruments means being proficient flying partial-panel. Pilots practice partial-panel regularly using the standby attitude indicator, but if it were off by 20 degrees in bank and five degrees in pitch, would it be good enough to help overcome disorientation? The standby attitude indicator can also precess rapidly. It used to be common to practice true partial-panel, i.e., using the altimeter and airspeed, vertical velocity, turn and slip and heading indicators. This type of flying is demanding and takes practice, but it pays dividends, particularly when a standby attitude indicator is added to the crosscheck -- the pilot can quickly determine any errors and compensate for them. Although spatial disorientation trainers exist, they are really only good at demonstrating the effects of the problem; they don't teach how it can be overcome. Simulators can provide some valid disorientation training, and the A-10 Full Mission Trainer (FMT) started delivery in June 2001. While not a full-motion apparatus, the FMT has good fidelity and permits pilots to practice a lot of things they can't do in the air because of safety limitations (double-engine failures) or time.

Investigators believe an Air Force pilot's severe spatial disorientation while flying in adverse weather conditions at night was a substantially contributing factor in the crash of an A-10A Thunderbolt II fighter aircraft 20 January 2000, according to an accident investigation board report released 23 May 2000. The accident occurred approximately 12 miles west of Gowen Air National Guard Base, Boise Air Terminal, Idaho. The pilot, Maj. Mark Moynihan, was killed and the aircraft destroyed in the crash. Moynihan was assigned to the 190th Fighter Squadron, 124th Wing, Gowen Air National Guard Base, Idaho. According to the report released by Air Combat Command, investigators could not find clear and convincing evidence to determine the exact cause or causes of the mishap. Investigators suspect severe spatial disorientation as the primary factor, possibly enhanced by cockpit distractions affecting Moynihan's navigation, lighting and radio equipment. The probable display of incorrect information on the main attitude director indicator, caused by a potential malfunction or the pilot's mistrust of that information during a critical phase of flight, may have amplified the spatial disorientation.

TF-34 engines are essentially two level maintenance via user Queen Bee sites at Barksdale, Davis-Monthan and Shaw AFBs. All ACC aircraft TF-34 engines are repaired at Davis-Monthan or Shaw AFB. Shaw AFB also supports USAFE. PACAF uses a combination of two and three level maintenance; Osan AB utilizes regional support provided at Kadena AB, while Eielson AFB performs Jet Engine Intermediate Maintenance (JEIM) on-sight. Barksdale AFB regionally supports AFRC. The ANG remains entirely supported by base field JEIM shops. Depot level engine maintenance is accomplished by the Navy at Jacksonville NAS, FL. The A/OA-10 has 51 avionics line replaceable units that transitioned to two level maintenance.

The A/OA-10 was designed for user maintenance in all normal maintenance inspections and tasks. This design has been very successful for this aspect and there is every expectation this will continue for the life of the weapon system. The only depot level requirements are Analytical Condition Inspection (ACI) and unscheduled depot level repair.

ACI is a specialized inspection to check areas, sub-systems or parts that are not checked on any periodic basis during normal maintenance. The purpose of the ACI is to find developing problems that might affect the mission or ensure such conditions do not exist. Problems discovered during ACI result in engineering studies that determine appropriate corrective action. There are 11 ACI aircraft selected (by usage, age, flight hours and environment) from different bases and MAJCOMs that are scheduled per fiscal year. The ACIs are accomplished at OO-ALC.

Unscheduled depot repair occurs when an aircraft incident, accident or other unusual occurrence creates a problem beyond the users ability to correct. Such occurrences result in a request from the MAJCOM for depot assistance. Depending on the situation, the aircraft may be inducted into a depot or contractor facility, or a depot or contractor field team may be dispatched to the location of the aircraft.

The A/OA-10 has a requirement for repaint every eight years. The fleet size sets the current requirement to approximately 65 per fiscal year. While this is not strictly a depot requirement, the need for a fixed, specialized and environmentally contained facility limits the user in his choices. The A/OA-10 is primarily painted atOO-ALC; however, Daimler-Benz AG in Germany paints USAFE aircraft. For economic reasons the 11 ACI aircraft inducted into OO-ALC each year are also painted.

The addition of the LASTE system and the pending installation of the EGI/CDU system have greatly increased the complexity of the A/OA-10 weapon system, including the troubleshooting and maintenance requirements. Also, the implementation of the 2-level maintenance system, eliminating the intermediate-level maintenance capabilities at the operating units, has necessitated improved troubleshooting capabilities at the unit levels to maintain the aircraft operational readiness requirements. An Operational Test System (OTS) has been developed to provide a computer test aid for the organizational maintenance units to expedite their maintenance actions. The OTS contains a software test program that requires periodic updates to maintain compatibility with the LASTE and CDU systems, as well as other A/OA-10 avionics systems.



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