MEL Magic — Is It Really Airworthy?
By Stephen P. Prentice
If a technician has not had the opportunity to deal with an MEL situation, he had better be prepared. MEL stands for minimum equipment list, and there is one for all transport category aircraft and now many general aviation type aircraft. Technicians in the air carrier business are most likely familiar with MELs and more importantly, the consequences of failing to properly handle equipment that is inoperative. Those in the general aviation field, however, may not be as well informed on the subject. A recent survey shows many cases where technicians have been sanctioned for their failure to observe the regulations regarding releasing an aircraft with defective or inoperative equipment and/or clearing the defect in the maintenance record.
A little bit of history may be in order. Back in 1986 the FAA Administrator interpreting the FAR in Washington decided that if something did not work on an aircraft, it was not airworthy and could not fly. FAA said that each item of installed equipment must operate. If it did not work, then the airworthiness certificate for the aircraft was invalid. Never mind that the aircraft was otherwise perfectly safe to fly and that for years there was no problem. This immediately cast a dark shadow on the business simply because some planes fly with equipment that is temporarily not working. It was generally left up to the pilot or operator to determine that it was safe to go. For many years of flying this worked very well. After all, maintenance and operations were paid to determine such things before the airplane could fly. But no more. The government had spoken. Well, what to do? FAA's answer was the magic of the MEL
The FAA had said at that time that since the equipment that was not working was a part of the original type certification for the aircraft, it had to work in order for the airworthiness certificate to be valid. Furthermore, any equipment added after type certification had to operate or else the certificate was invalid. If something was missing, the certificate was null and void. There had to be some change to the aircraft type certificate in order to get around the fact of the defective equipment. Then just like magic, the MEL was made a part of and became a supplement to the type certificate.
The MEL was around for some time in the air carrier business. Now its application was broadened. It became the answer to the invalid type certificate.
HOW IT WORKS
There has to be a means of safely operating the aircraft while certain items or systems are inoperative. However, all items listed on the MEL are subject to specific limitations and handling procedures. This is where the problems come in. It is simply a listing of various equipment and instruments installed on the aircraft. Items such as engine controls, electronics, and other accessories are included. When something fails to work on the aircraft, the pilot or maintenance technicians will get the MEL book and look the item up. If the book says you can fly without it, you go. If not, you stay and fix it. In addition, these items are all categorized with regard to when they have to be fixed. Some items are allowed to be deferred inoperative for greater periods of time than others. It just depends on their relative necessity to safely operate the aircraft. Deferred is the operative word in the maintenance record of the MEL world.