MROs Developing the Air Carrier Interface

The interface between maintenance repair organizations (MROs) and their air carrier customers is a complex stew of individual processes meant to meet each other’s regulatory requirements but developed separately. Each is based on experience, regulatory interpretation, and return to service goals. MROs must work on each operator’s aircraft in accordance with applicable provisions of its maintenance and inspection program. Each operator is separate but equal. As a result, it’s not uncommon for an MRO to have similar make and model aircraft side-by-side, worked to different requirements and processes aimed at compliance to the same regulations.

In planning work on an operator’s aircraft, the MRO tries to accommodate the unique maintenance program of each carrier. By combining the operator’s processes with its own it is able to provide the necessary services to deliver an aircraft. Such efforts are not without their challenges.


The hangar plan evaluates hangar space and dwell time for each hangar position. In a nose to tail schedule, the area must have the flexibility of allowing aircraft movement. Production plans allow for use of the hangar space for a predetermined period of time. Based on an operator’s program, the scope of inspection may drive use of the space over irregular periods. Two similar airframes may come in for a C check but the scope of inspection for either creates different dwell periods for the aircraft. One aircraft will sit 10 days; the other three weeks.


Managing tooling is a major headache for the reason that there is so much of it and it all costs a fortune. Equivalent tooling may be used. Having a robust equivalent tool development process can pay dividends in cost savings without impacting safety or compliance. However, it’s possible that certain carriers may restrict the MRO to only using manufacturer’s authorized tooling based on its process standards. Other carriers do not have a problem with equivalent tooling.

Tooling issues should be resolved well in advance to assure that production stoppage or bottlenecks don’t occur. The MRO’s quality unit needs to scope these requirements in advance of an operator’s arrival. The air carrier’s quality unit should be able to provide advance knowledge of these issues.

Current data

Most air carriers can provide current data for their aircraft. In fact when aircraft are customized to the operator’s specification it’s usually the only way. Operator’s manuals arrive in a variety of media. It’s not uncommon for classic aircraft operators to continue to have microfilm. Newer aircraft have a better time of it since they come with electronic media access. In this case the problem is more about access since the station where these data are located can be away from the aircraft and there is a line to use it.

One aspect of technical data that an MRO must control is the availability of “reference only” material. Technicians may hang on to obsolete data if access to computers or readers is limited by availability. Printed media left from other projects will find themselves in use if the processes for their control are weak. Data from one carrier’s 737 may show up on another without processes in place to prevent it.

Printed hardcopy from electronic media must be date stamped for the job and then at a designated time discarded. Old hard copy manuals may have value only if the MRO is maintaining classic equipment and the revision can be determined the most current. Otherwise they should be retired to a dumpster in a condition that precludes retrieval by inquiring minds and idle hands.


Effective training is necessary for the success of any project. Training goes beyond technical matters. MROs need to educate everyone involved on the carrier’s unique requirements defined in their general maintenance manual. In each carrier’s manuals lies its own method of record keeping, task card design, inspection criteria, part certification requirements, engineering criteria, and technician qualifications. The processes of two B-737s parked together in a hangar bay may have different required inspection item (RII) listings. MRO personnel need to be ready to learn the difference between the carriers. The differences create a rich environment for errors.

There may be different signature requirements for each operator in the hangar. One accepts a stamp; another requires a full signature and A&P. Both are part of each carrier’s maintenance program requirements. Corrective action signoffs must follow a set format for one carrier and completely different for another. When working hundreds of tasks these small differences matter.

If personnel are coming off one project to work this new aircraft they must be counseled on the importance of accepting the new rules established by the new customer. QA personnel must attend as well to give them the necessary tools to maintain oversight of the check program details. The key here is to educate personnel into accepting new work habits for the project. MROs must master the art of change.

Failure to understand the carrier’s requirements can result in unplanned requirements that degrade the repair station’s internal administrative processes. For example: The use of a duplicate nonroutine process that is not compatible with the repair station work order program. The repair station may have to create and manage duplicate work records based on the carrier’s need to maintain its internal nonroutine records in a computerized system. This activity has an impact on check performance since the check personnel must correctly record work using two different methods.

Adequate personnel

There has to be enough people to do the job. They have to be knowledgeable enough to do the job well. Heavy checks having thousands of man-hours need to be staffed with enough qualified personnel to assure that the aircraft meets inspection program requirements. It also has to deliver the aircraft at the time necessary to meet its internal production plan.

One key concern is the use of noncertificated personnel. Operators are wary of their use but each MRO mitigates the concern by putting controls in place to assure that effective oversight is maintained. Instructions to noncertificated personnel have to be clear as to what they can and cannot do and be described in the repair station manual. Inspection buy back would be one control.

In extreme cases the operator’s program can prohibit the use of noncertificated personnel. It impacts other lines of work due to the need to shift certificated personnel to the new project. One operator can affect the check performance of many others. It may also impact back shop support. Structures personnel, for example, may be noncertificated but highly skilled in their specialty. Nondestructive testing personnel would be another example. A&Ps having lesser overall experience but greater specialized skills may be tasked with these specialty functions.

Communication a must

Every heavy check has a production method. In developing the check plan, the use of personnel requires management of technicians to a schedule that includes a labor budget. This allows the manager to task the aircraft daily to a set performance level gauged to deliver the aircraft on the target date and meet the repair station’s revenue goals.

Each carrier brings its own production expectations to the project. Management of these expectations requires robust communication on what takes place daily. Daily production reports that provide a clear description of the check progress are a must. The report must be credible and readable. Negative information must be there as well as positive. If production is impacted the reasons why must be there to explain project recovery.

MROs have a tough job. The interface between the MRO and each of its customers is a highly fluid environment requiring good communication and management skills. Each operator’s individual maintenance program requirements must be met. MROs must plan to the individual interface created by each operator that rolls into their hangar and create the necessary relationship that results in a high level of quality and on-time delivery of an airworthy aircraft.

Vern Berry’s maintenance experience within the aviation industry includes key management roles in quality and safety for both MRO and air carrier operations.