Pilot Training Minimum Equipment List

Overview The MEL has a lot of information helpful to pilots. To familiarize you with the MEL we will look at: ◦MEL Overview ◦Engine Control example ◦Special Operations

MEL Overview

When do I need to use the MEL? Whenever repair or replacement of unserviceable units cannot be made prior to departure.

What do I use the MEL for? You use the MEL to permit operation with inoperative items of equipment for a period of time until repairs can be accomplished. Remember the MEL sets minimum requirements. It does not relieve maintenance and the captain from determining that the aircraft is in a safe condition for flight.

Repair Intervals Required components have different time allowances before repair.

The airplane separates messages that are MEL related as well as prioritizing all messages for effective use

Here’s how they are prioritized

General Operating Procedures Note that the MEL sometimes provides general operating information unrelated to a specific failure.

In-Flight Consultation The MEL also provides operational information for certain in-flight failures

Engine Control Example First let’s have a short review on the engine control system Then we will see how faults effect dispatch

ECU An ECU controls the engine thrust based on inputs from the thrust lever. The ECU modifies the thrust based on inputs from airplane and engine systems. This makes the thrust setting more accurate and maintains limits.

Electronic Control Recall there are no cables connecting the thrust levers to the engine. All signals are electronic. If the ECU fails, then the engine cannot be controlled.

Redundancy Each ECU has two separate channels. Only one channel controls the engine at a time. The other channel is a backup.

Normal Mode Whichever channel is in control adjusts the thrust level for ambient conditions in the normal mode. To do this, the ECU’s need information from the Air Data Computers (ADC’s)

Reversionary Mode If both channels lose the required inputs (ADC’s), then the ECU can no longer adjust thrust to the outside conditions. This degraded mode is called the alternate mode.

Reversionary Mode Indications When this happens, the EICAS message L(R) ENG EEC MODE appears and the ALTN light turns on.

ENG EEC MODE Checklist You first perform the associated checklist

On Ground Procedures Recall according to normal procedures you also check the MEL in addition to the checklist after engine start if this occurs while you are still on the ground.

Cross Reference List A cross reference list allows you to locate the information based on the EICAS message. Note that the message is alphabetized based on the L or R first.

MEL Note that is not specifically for the L(R) ENG EEC MODE message. It is for all EICAS messages related to the EEC.

Electronic Engine Control Failures In this example, the header messages are based on the associated status message. The alert message is found in the Operations section. Associated status Continued

ECU Faults We saw what happens if the ECU cannot get all the data it needs, now let’s look at what happens if the ECU computers (or channels) have failures.

ECU Fault Indication Recall that Each ECU has two channels. Each channel is like a separate computer. Faults occurring in the channels are associated with different EICAS messages depending on their severity.

EICAS Message Priority Recall that EICAS messages are prioritized based on their urgency.

Status / Maintenance Faults Faults not requiring immediate attention are identified by a maintenance level message L(R) ENG C2. Faults requiring dispatch attention, but still allowing dispatch appear as a status level message L(R) ENG C1.

Alert Messages The alert messages L(R) ENG CONTROL or ENGINE CONTROLS appear to indicate faults after engine start. L(R) ENGINE CONTROL appears after engine start to draw attention to dispatch- able faults. ENGINE CONTROLS appears after engine start to prevent dispatch with the failure. (only occurs on ground < 80 kts)

ENGINE CONTROL Checklist In either case you go to the ENGINE CONTROL(S) checklist. Note the lack of anything operational in the checklist, Again you must check the MEL In either case you go to the ENGINE CONTROL(S) checklist. Note the lack of anything operational in the checklist, Again you must check the MEL

Cross Reference List The Cross Reference List sends you to the same place as before.

Electronic Engine Control Failures Notice you can dispatch with C1 or C2 faults but not with the ENGINE CONTROLS message (Note 1) Continued

MEL items without EICAS message

EEC ALTN Light Failure What happens if a key indicator light fails. Let’s look at the EEC ATLN light on the EEC switches. A failure of this light does not cause an EICAS message to appear. In this case you must look up the failure according to the ATA chapter.

EEC ALTN Light Failure You find there is relief, but you have some limitations. Next let’s look at one last Engine thrust example without an EICAS message.

Thrust indication Failure A TMC display failure occurs if the Thrust Management Computer does not compute thrust limits. In this case, these indications disappear from EICAS. This is the only indication for a TMC display failure. (i.e. No EICAS message)

Engine Bleed Sensor failure Note that the indications do not disappear for just a TMC failure but also for lack of information to the TMC. Here the TMC can’t compute limits because of a loss of engine bleed input.

Fault with no EICAS message Since there is no EICAS message, you cannot use the cross reference list. You must use the ATA chapter, in this case it is Engine indicating ATA chapter 77. To dispatch, you need an alternate means of thrust setting. Where would you find that?

Performance In- flight - QRH How about the performance in-flight section of the QRH? (also duplicated in Volume 1 of the operations manual) Here are the Max Climb limits for example.

There are also tables for Max Continuous operation

Special requirements based on operational approvals Now we will look at how special operations affect dispatch in the MEL Aramco is approved for RVSM, PRNAV, ER operations, and Low visibility approaches Let’s look at how these are reflected in the MEL

RVSM and/or ER Operations Autopilots, for example, are not required unless RVSM and / or ER operations are conducted. Next let’s look at Cat II/IIIb limitations

Low Visibility Operations - MEL The low visibility required equipment is stated a little differently. They are identified as approach minimums do not require their use. Notice the operations note at the bottom, it refers you to the General Maintenance Manual. Let’s have a closer look at this. But first let’s have a quick look at the Aramco Cat II/IIIb manual.

CAT II/IIIB Manual For an overview of what systems are required for low visibility operations, consult the Aramco Cat II/IIIb manual. Notice the Cat II/IIIb manual requires you to reference the MEL and GMM.

AAC 767 GMM For a more detailed list of the individual components required in those systems, maintenance needs to check the GMM

PRNAV example Finally, here’s an example where Flight management computers are not required unless you will be conducting PRNAV operations.

Summary In this module we covered: ◦When you use the MEL and its purpose ◦How EICAS messages are organized ◦How to use the MEL through engine controls examples ◦Faults which do not have an EICAS message ◦How special operations are identified in the MEL