Aircraft Maintenance In an EASA Environment Introduction

Sofema Aviation Services www.sassofia.com considers an EASA Compliant Maintenance Planning Process. 

Maintenance has come a long way since the early days when maintenance programs owed more to the perception of the maintenance needs, as opposed to the analyzed and justified needs. In addition the role of the regulator was also minimal, and in part developed as a result of events, incidents and accidents. 

During the end of the first half of the 20th century regulations began to strengthen and the aircraft manufacturer was seen as the appropriate source of the maintenance program development. The early attempts at effective maintenance (in the 1960’s) saw time limits developed which resulted in aircraft being progressively dismantled, in what became know as Hard Time primary maintenance.

All hard time components were then routed through an overhaul process and after an appropriate restoration process were considered as zero timed. (Means they were considered as zero life and good to go again) - Following investigations into the effectiveness of the Aircraft Maintenance Process, by both the FAA and several airlines, a number of determinations were made.

When dealing with the complex technical systems involved in air transport, the consequences of unreliable services become critical and may include - A high cost of operation, A loss of productivity, Incidents, and potential exposure to accidents. 

Hard Time Primary Maintenance

The early attempts at delivering a more effective maintenance approach (in the early 1960’s) saw hard time limits developed which resulted in aircraft being progressively dismantled, in what became known as Hard Time primary maintenance.

All hard time components were then routed through an overhaul process and after an appropriate restoration process were considered as zero timed. 

Essentially this meant that they were considered as zero life and good to go again for a full life – the problem was that the overhaul process did not necessary impact the eventual life of the component. 

Through the 1960’s representatives from both the FAA and a number of airlines formed a task force to investigate the capabilities of preventive maintenance. The data they gathered was analysed with the following outcomes. 

The process of scheduled overhaul had little effect on the overall reliability of a complex equipment unless the equipment has a dominant failure mode (Means unless there was a specific item which would wear out the entire overhaul process did not add value).

There are many items for which there is no effective application for scheduled hard-time maintenance.

On Condition (OC) Maintenance 

The findings of the task force led to the development of a second primary maintenance process defined as On-Condition (OC). On-Condition requires that an appliance or part be periodically inspected or checked against some appropriate physical standard to determine whether it can continue in service. 

The purpose of the standard is to remove the unit from service before failure during normal operation occurs. 

From the regulatory perspective it is of primary importance to deliver effective oversight of aircraft operators’ maintenance programmes. Together with a viable assessment of the management of the continuing airworthiness process.

Apart from the safety (which is almost taken for granted) a reliable service with on time departure is a part of the passenger expectation, as a result this has made the on-time performance of an airline’s schedule a key factor, which places Airlines continuously under pressure to improve their punctuality and provide on-time performance.

Eventually all mechanical components or equipment's will fail, the whole purpose then of maintenance is to not only to recognize this fact but to cope with it in the most effective way.

**** Overhaul Viability - Reality Check ****

In reality it was understood that schedule overhaul did not have a particular impart on the reliability of a component – unless there was a dominant failure mode evident (Thus calling into question the associated rational in performing the overhaul).

 **** Scheduled Maintenance Viability - Reality Check **** 

A second understanding concerns the fact that there are many items for which there is no “effective maintenance activity” for scheduled hard time maintenance. 

An outcome of this understanding (of the effectiveness of the maintenance process) was the development of a secondary primary maintenance process, which we know today as On condition maintenance “OC”. 

With On Condition Maintenance we ensure that the component or system is maintaining conformity with the expected behaviour (a standard) and any deviation will be the trigger to remover the component from service.

Our mission is to share that the role of Maintenance Planning has the potential to provide significant savings whilst maintaining a fully compliant and safety focused maintenance management system.