Question

What are the risks and benefits of maintaining aging aircraft? What about maintenance costs, fuel efficiency, and emissions? Be sure to think beyond the questions posed here and consider all aspects of the aging aircraft in domestic and international aviation.

Answer 1

An aircraft begins to ‘age’ as soon as it first flies and various effects of aging begin to occur almost immediately. However, the term is usually applied to the issues which can begin to arise as the time-since-new becomes significant - and greater than the average age of similar-class aircraft. Here I have mentioned some of the risks of maintaining aging aircraft, as follows

RISKS:

Metallic Corrosion: Metallic Corrosion occurs when chemical action causes deterioration of the surface of a metal. Most corrosion is galvanic or electrolytic in origin, which means that it has occurred because two dissimilar metals have been together in an electrolyte. This effect can also occur at the microscopic grain boundaries within a metal alloy. However it arises, it may go undetected and result in loss of integrity of metallic structures and leads to failure, so while maintaining the aircraft we have to ensure that it does not remain in contact with the contaminated water for a long period of time.

Structural Failure:de-bonding and fatigue damage which is the main reason to lead to failure. For that aircraft at least, the introduction of static test hulls with simulated hours and cycles kept well ahead of equivalent in-service aircraft is not sufficient. The possibility of structural fatigue from any origin has been actively considered since the advent of pressurized aircraft when there were accidents attributable to an insufficient understanding of some basic design issues. Since then, aircraft design procedures have involved the carefully-researched creation of structures which will withstand a stated number of flight cycles and/or flight hours with a low probability that the strength of the structure will degrade below its designed ultimate strength before the end of its approved life.

Routine Maintenance: The first reason for the increase in Maintenance cost due to age is linked to the Routine maintenance1: the number of Routine tasks to maintain the aircraft increases with age. This is mechanical: independently of the
aircraft utilization, as the aircraft ages, and there are additional tasks to perform. This is driven by the
scheduled maintenance as defined by the maintenance program documents such as the A/C manufacturer’s
MPD, the OEMs' requirements and the specific operator’s maintenance related program for the aircraft and
the cabin.It is divided into following 3 categories

1)Standard Routine Maintenance

2)Third Party component routine maintenance

3)limit Of validity incurred maintenance

Non-Routine MaintenanceThe second reason for increasing costs is linked to the Non-Routine maintenance: the material properties weaken over time due to the environment, the stress of normal operation and the system utilization. This can
generate findings (fatigue, damage tolerance) like cracks or corrosion, which are expected to increase over
time until the part is repaired or replaced. The need for Non-Routine maintenance can be identified by Routine maintenance inspections or by unexpected faults and failures. Though structures are qualified for continuous airworthiness requirements,
the aircraft structures are been sized for a design life objective, when the aircraft is approaching this target
the probability of having findings increases. Cracks may initiate but are controlled through inspections to
prevent failure of the material.