A brief explanation of American’s maintenance check procedures:

"PS" Daily Checks
Each aircraft is checked every 2-3 days in its "PS" (Periodic Service) check. The aircraft is visually inspected and its maintenance log book is checked for entries and maintenance needs. The "PS" check can be performed overnight or during downtime during the flight day. It averages approximately two man hours.

"A" Checks
The "A" check is more detailed than the "PS" check. "A" checks are performed every 7- 9 days (approximately 80 - 100 flight hours). The "A" check is performed at one of 40 stations around American’s system. It averages 10 - 20 man-hours.

"B" Checks
The "B" check is an even more thorough maintenance check. The "B" check is accomplished approximately every two months (roughly 500 - 600 flight hours). Besides specific service performed on
the aircraft, a detailed series of systems and operational checks are performed. American always
performs "B" checks inside one of its hangars at seven different cities around its system. A "B" check requires approximately 100 man-hours on narrowbody aircraft (those with only one aisle) and approximately 200 - 300 man-hours on widebody aircraft (those with two aisles).

"C" Checks
The "C" check is the most thorough type of maintenance work performed by American. The airframe - virtually the entire aircraft - goes through an exhaustive series of checks, inspections and overhaul work. It is performed at either of American’s heavy maintenance and engineering centers in Tulsa, Oklahoma Maintenance Facility. There are different levels of "C" checks depending on the type of aircraft.

• Narrowbody "C" Checks
American does two types of "C" checks on its narrowbody planes. The first is a "Light C" check, which occurs approximately every 15 - 18 months. It requires approximately 2,100 man-hours and three days to accomplish. Every fourth "Light C" check becomes a "Heavy C" check. This check requires 20,000 - 30,000 man-hours and takes from three to five weeks to
accomplish.

• Jet Engine Overhauls
Modern jet engines are among the most reliable devices in aviation. American does not replace and overhaul jet engines at a specific number of hours. Instead, American uses a 24-hour-a-day "condition monitoring" process that scientifically tracks the condition of every engine on every aircraft. Besides visual inspection, technicians monitor the internal condition of every engine, using such procedures as boroscope inspections and oil sample spectographs. The goal is to replace and overhaul an engine before a problem can occur. Engine overhauls are performed at the Tulsa Maintenance and Engineering facilities. The engine replacement is usually performed at one of the six "B" check hangar locations around the country