Development of a Maintenance Control Centre (MCC) Defect Procedure

Sofema Online (SOL) www.sofemaonline.com considers managing MCC Defect Processing and Actions

Introduction - Development of a Defect Control Procedure – Example Short Content

A description of the defect rectification and control procedures, including details of:

o The methods used to detect and report recurring defects.
o The procedures for scheduling the rectification of defects whose repair has been deferred..."
o Procedures for recording and rectification of defects, including the identification of recurring defects.
o The complexity of the system used to control defects, including rectification and deferral, as well as identifying and handling recurring defects will vary according to the type of aircraft operated and the size and nature of the operation.

o It may include policies and procedures for the use of an approved Minimum Equipment List (MEL).
o The pilot in command must know the status of the aircraft in order to make an informed decision on its serviceability for the intended flight.
o Additional crew workload must be taken into consideration if defects are deferred.

Development of a Defect Control Procedure – Example Long Content

Defect Control Procedure

Purpose: To establish the procedure and instructions for the situations when technical discrepancies are deferred as an ADD or cleared and a request for an extension of a MEL item should be made.

Definition and Abbreviations:

>> ADD: Acceptable Deferred Defect;
>> CDL: Configuration Deviation List;
>> DDG: Dispatch Deviation Guide;
>> MEL: Minimum Equipment List;

A Recurring Defect is defined as a defect or defects of the same nature, which has been recorded more than once in the Technical Log within 7 flights (or 03 consecutive operational days) where troubleshooting action(s) did not rectify the defect. 

Deferring Defect and MEL Application

>> In order to maintain flight schedule integrity, it occasionally becomes necessary to defer the correction of minor discrepancies until maintenance can be accomplished.
>> MEL items will not be applied to aircraft if at the main base and

o Qualified maintenance personnel are on duty;
o The necessary facilities and equipment are ready, and
o Required parts, appliances, components, tools or materials to perform the necessary repairs are available.

>> All deferrals will be authorized for a specific repair interval. If the repair cannot be implemented within the MEL repair interval the MEL overrun Procedure may be applied.
>> ADDs are split into two groups in the Technical Log:

o MEL/Airworthiness related ADDs (These ADDs are those related to the MEL/Airworthiness requirements and will additionally include all defects that are within the Approved Maintenance Manuals (SRM, AMM etc.) limitations.)
o Non-MEL related ADDs These ADDs are those of a minor nature with no airworthiness implication.

Raising & Clearance of ADDs

When raising, progressing or clearing an ADD it is necessary to complete an entry on the MEL or Non-MEL related ADD sheets as well as on the Technical Log page.

>> A note to crews and engineers, form must be raised to inform all flight crews and maintenance engineers working further on the aircraft of the recurrence of the defect;
>> An additional note: “THIS IS RECURRING DEFECT, REOPEN ADD BXXX” must be also entered in the technical log and related ADD reference list.

Concerning Defects Outside of the MEL

The deferment of any defect found during maintenance that is not addressed by the MEL or CDL, such as cracks and other structural defects or damages may be necessary in certain cases.

The Maintenance controller shall investigate, in consultation with the PART-145 AMO, whether the damage is within the limits described in the manufacturer’s publications

(e.g. structural repair manual, repair drawings, etc.) in order to allow deferment.

If this information is not available, the aircraft manufacturer / TC Holder shall be contracted in order to provide a temporary repair (note the responsibility for certification and acceptance of the approval rests with the EASA Part 145 Organisation.

Additional Procedures May be Developed in Respect of any of the Following Tasks

>> Any defects reported by the flight crew or found by the maintenance provider during layovers.
>> AOG & Out-of-Service Support Activities.
>> Identification of Recurrent Defects & Trends.
>> Issue of Rectification Work Packages.
>> Investigations into significant issues.
>> Monitoring of Fluid Consumption of engine oil and hydraulic fluids based on available data to identify negative trends.
>> Management of Minimum Equipment List (MEL) and Configuration Deviation List (CDL) deferrals with maintenance provider.

Next Steps

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Sofema Aviation Services provides a 2-day course to implement your own MCC – Defect Control Process. Check it out