Aircraft maintenance is the action necessary to restore or maintain aircraft parts in a serviceable condition. The process entails inspection, repair, modification, servicing, determination of the condition, and overhaul. Without an effective inspection and maintenance program, no aircraft can be tolerant of neglect that it can be safe. The conditions that affect aircraft deterioration with age such as fatigue, corrosion, and wear.
The main purpose of conducting aircraft maintenance is to maintain the aircraft in a state that allows issuing a certificate of release to service.
Essential Reasons for Carrying Out Aircraft Maintenance
All aircraft must go through maintenance. It is not necessarily that the maintenance is done in the hangar. However, the hangar environment is suitable for the light maintenance of the aircraft. The following are some of the important reasons for carrying out aircraft maintenance.
- Aircraft safety- airworthiness is the heart of every aircraft.
- Maintain an aircraft in service-availability of an aircraft is the key significance to all operators as the aircraft can meet its schedule.
- Maximizing asset value- keeping the asset value is of prime significance to the owner.
Maintenance involves corrective and preventive work. This is important in ensuring that there are no undetected failure chances. Inspection is also crucial in monitoring aircraft deterioration. Additionally, preventive work is carried out to avert and anticipate any failures. However, there are two conditions that preventive work should meet to ensure that it is worthwhile.
- After maintenance action is complete, the item must be restored to its original reliability.
- Maintenance cost must not be more than the failure it is intended to avert.
Types of Aircraft Maintenance
Aircraft maintenance checks can be classified as scheduled maintenance, preventive maintenance, corrective maintenance, and predictive maintenance.
Line Maintenance
Line maintenance is also known as light or stand-alone maintenance. It typically involves daily checks, pre-flight checks, and minor scheduled maintenance tasks.
It is done on the general airframe of an aircraft daily between 24-48 hours. Other times it can be done weekly between 7-8 days.
It is usually done outside the hangar.
It is limited to 500 flight circles.
Since most of the maintenance work is lighter, it is easy to set up. Line maintenance includes;
- Minor repairs that don’t need vast disassembly and can be completed by simple means with the use of specialist aircraft tools.
- Troubleshooting.
- Defect rectification.
- Using external test equipment where necessary for replacing components like engines and propellers.
- Preventive work requires a visual inspection to detect the obvious failures. However, it does not need vast depth inspection.
Heavy Maintenance
Many people refer to it as base maintenance. It involves tasks that are long-lasting and are generally in-depth. The maintenance is also conducted less frequently. Undertaking heavy maintenance, maintenance, repair, and overhaul requires large facilities, specialized equipment, and crew. Several activities take place during this maintenance.
- Defect’s removal.
- Technology upgrade
- Cabin painting and configuration
- Check C
Check C involves inspections of large majority components, and it is performed after 20-24 months.
It is also referred to as light structural maintenance. It includes checking on;
- Corrosions.
- Specific high parts of the airframe.
- Cabin upgrade, e.g., entertainment system and new seats.
- Carpet replacement.
Check C takes between 1-6 weeks and requires a 6000-man hour to complete the maintenance.
Component Maintenance
Component maintenance is also known as check D maintenance.
It entails and is extensively a check and maintenance on all parts of the aircraft.
Generally, it is a very demanding process for all aircraft.
It is usually performed between 6-10 years and can only be carried thrice before scrapping off the aircraft.
During this process, inspection and overhaul are done on the entire part of the aircraft, removing all the paints to enable fuselage and airframe inspection.
It takes 50,000-man-hour to complete the work.
The whole maintenance process can take up to two months and may require small maintenance space because some parts of the aircraft may be established in the workshop.
Due to the more tremendous efforts, it has proven to be the most expensive check. A single check on middle-level aircraft causes millions of dollars as it involves structural work and interior design.
Maintenance Intervals
Maintenance intervals are set parameters within the Approved Maintenance Schedule. It is based on the maintenance planning document. Maintenance intervals are set according to the criteria, mostly depending on how well failure is predicted and the damage detected. The following are the different criteria in which aircraft maintenance intervals are set;
Hard Time
This is a maintenance level in which the preventive process of a known deterioration of an item is limited to an acceptable level. It is performed in periods related to service time.
On-Condition
This is a preventive process that involves inspection or testing of an item to an appropriate standard at specific periods to ensure whether it can continue in service or not.
This kind of inspection determines the need for maintenance action.
The key importance of performing an on-condition is to eliminate an item before it fails in service.
Units for Aircraft Maintenance Intervals
Flight hours are for aircraft parts that are in operation continuously.
Flight cycles involve the items in operation once or twice per flight, such as air starter, landing gear, hull pressurizations, and brakes.
Calendar time, a unit for items on exposure such as corrosion to structures and fire extinguishers.
Operating hours are usually for independent flight hours and flight cycles, such as auxiliary power unit operations.
Importance of Aircraft Maintenance
There are various reasons why aircraft maintenance is regulated in every part of the globe. The following are some importance of aircraft maintenance.
Passenger Safety
Through regular maintenance and checks, passengers travel safety is guaranteed as passenger safety is the priority of any airline.
Aircraft life-cycle
Regular maintenance prolongs aircraft life, ensuring that it performs safely for the expected time. An aircraft should undergo various levels of inspection to take effective preventive measures.
Maintain Great Performance
Constant maintenance ensures that the aircraft is in a serviceable state for its flying period. Pre-flight operational checks also ensure that no failure occurs before any trip.
