The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
New Materials for Next-Generation Commercial Transports
TABLE 7-1 Typical Airline Maintenance and Service Plan
When Service is Performed
Type of Service Performed
Impact on Airline Service
Prior to each flight
''Walk-around"—visual check of aircraft exterior and engines for damage, leakage, and brake and tire wear
None
Every 45 hours (domestic) or 65 hours (international) flight time
Specific checks on engine oils, hydraulics, oxygen, and specified unique aircraft requirements
Overnight layover service
Every 200–450 hours (22–37 days) flight time
"A" check—detailed check of aircraft and engine interior, services and lubrication of systems such as ignition, generators, cabin, air conditioning, hydraulics, structure, and landing gear
"C" check—detailed inspection and repair program on aircraft engines and systems
Out of service for 3–5 days
Every 2 years (narrow-body aircraft)
Inspection and reapplication of corrosion protective coatings
Out of service up to 30 days
Every 3–5 years
Major structural inspections with attention to fatigue damage, corrosion, etc. Aircraft is dismantled, repaired, and rebuilt. Aircraft is repainted as needed
Out of service up to 30 days
monitoring, and no preventive maintenance is required or desirable. Modern aircraft are more tolerant of failures than older aircraft designs because of the increased redundancy provided in the design.
Generally, most airlines classify specific component maintenance tasks as follows:
lubrication or servicing, where the replenishment of the consumable reduces the rate of functional deterioration;
operational or visual check, where identification of the failure must be possible;
inspection or function check, where reduced resistance to failure must be detectable and the rate of reduction in failure resistance must be predictable;
restoration, where the item must show functional degradation characteristics at an identifiable age, have a large proportion of units survive to that age, and be able to be restored to a specific standard of failure resistance; and
discard, where the item must show functional degradation characteristics at an identifiable age, and a large proportion of units are expected to survive to that age.
Malfunctions of components should be evident to the operating crew, have no direct adverse effect on safety (whether they occur as a single or multiple event), and minimize the effect on the operation of the aircraft itself.
SERVICE EXPERIENCE
Effective application of new materials on commercial aircraft requires the designer to consider potential sources of damage or degradation in operating environments and to develop a maintenance and repair approach to address them. Damage may occur due to flight loads, thermal and environmental cycles, and aircraft operation and servicing activities. A number of valuable lessons have been learned from
