It is O dark thirty and the aircraft has been on the line for the past hour in anticipation of transporting the company president and several high-ranking executives to the annual stockholders’ meeting. The flight crew has already completed the initial power on checks when the passengers begin to board. Punctually, the limo arrives and the lone occupant embarks up the stairs into the aircraft cabin. Upon noting the arrival of the top banana the crew begins the sequence of starting engines. The main entry door closes, remaining engines are brought on line, and personnel are in place waiting to marshal the aircraft to the taxi way.
Standard company operating procedure calls for the use of the taxi light to signal ramp personnel that the aircraft is ready to taxi, after several minutes and still no taxi light, the unthinkable happens. The main engines are shut down, a message crackles across the communications radio in the hangar, “We have a problem and need the assistance of maintenance.” The lone on-call technician quickly approaches the aircraft as the main entry door opens. Upon entry the first words the technician hears are those uttered by the top executive, “Will this take long?” The response to this question has the potential to be career altering.
Although the above situation is dreaded by most there are several precautions that can make it less stressful. Safety, legality, and passenger comfort are some of the main considerations when deciding if an aircraft is fit to fly. Many aircraft passengers may already be plagued with a fear of flying and hearing that the machine that is about to carry them may not be safe to fly can cause a sudden and uncontrollable adrenaline rush prompting emotional outbursts. Thorough knowledge of systems and knowing who can answer specific questions are some essentials in minimizing departure delays.
In the United States, Federal Aviation Regulations (FARs) may provide some relief when it comes to component or system failures on various types of aircraft.
In FAR Part 91 references are made to Inoperative equipment:
instruments and equipment
(a) Except as provided in paragraph (d) of this section, no person may take off an aircraft with inoperative instruments or equipment installed unless the following conditions are met:
(1) An approved Minimum Equipment List exists for that aircraft.
(2) The aircraft has within it a letter of authorization, issued by the FAA Flight Standards district office having jurisdiction over the area in which the operator is located, authorizing operation of the aircraft under the Minimum Equipment List. The letter of authorization may be obtained by written request of the airworthiness certificate holder. The Minimum Equipment List and the letter of authorization constitute a supplemental type certificate for the aircraft.
Minimum Equipment List
Existence of a minimum equipment list (MEL) can be confirmed by the aircraft manufacturer. However existence is only part of it. Per the regulation, the document has to be approved by the airworthiness authorities and then adapted to the specific aircraft. Once the FAA master MEL is customized to a specific aircraft, the FAA office having jurisdiction over the aircraft operator will review the document and based on satisfactory findings, will issue a Letter Of Authorization (LOA). Only then is it legal to operate under the exemptions listed. It is also important to note that if a system or component is not mentioned in the MEL then it does need to be operational for flight.
The format of the MEL will often address aircraft systems, showing how many like devices are installed along with how many need to function to allow a safe flight. In certain situations flight procedures may require modification or maintenance action may be necessary to disable, test, or placard various inoperative systems or components.
In this issue we will look at the regulations that govern the operation of an aircraft when instruments and or equipment are inoperative.
Operating an Aircraft With inoperative instruments or equipment Joe Hertzler The MMEL is the Aircraft Evaluation Group’s method of relaying to us which items of equipment are...
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