I was talking to a friend yesterday who works for one of the US3 and he mentioned something about the MEL during a conversation regarding the 744 (guess that gives it away). When I asked him what the MEL was, he said there was three main OEM lists airlines use:

NEF- Non-Essential Furnishings
MEL- Minimum Equipment List
CDL- Configuration Deviation List

He didn't have enough time to elaborate on this, but what exactly is on these lists?

Items that can be inoperative or missing. However, the aircraft can continue to operate safely with associated performance/ops restrictions applied.

NEF can be like a coffee pot or toilet paper holder.
MEL can be the APU, GPS, assorted lights.
CDL are items that may be missing... panel doors, static wicks, etc.

Here is the master Boeing 737 MEL document from the FAA. http://fsims.faa.gov/wdocs/mmel/b-737%20r54a.pdf

The actual MEL items can vary carrier to carrier, depending on what they've been approved for and what their aircraft are equipped with. Many MELs also come with some kind of deviation from standard procedures as well. A quick example which comes to mind is that 737NGs can have 1, 2, or 0 HUDs (at my carrier, only the captain has a HUD). If inop it can affect what kind of instrument approaches can be performed and the minimums for those approaches.

NEF may just be a galley table, or interior panel.

Off the top of my head I can't think of what would be on a CDL

For example, I've been on a 737-400 with MEL 21-15. Outflow valve had to be removed and we were limited to unpressurized flight at or below 10,000 feet. It was a short flight FAI-ANC and ended up becoming a ferry because ops didn't want to fly passengers on an unpressurized plane.

A landing gear door might be an example of an item from a CDL. There would be a performance penalty for missing a landing gear door.

packmedic wrote:

Off the top of my head I can't think of what would be on a CDL

CDL items are things that would affect the aerodynamic characteristics of the aircraft. Some of the things found on the CDL:

External power access doors
Cargo door control access doors
Flying gear doors
Flap canoes (fairings)
Flight control surface seals
Winglets

Most of these items will incur a weight or speed penalty. We set a 30 day limit on CDL items, unless superseded by the MEL, e.g. a blocker door on a reverser can be missing (30 day), but will usually require the reverser be locked out (10 days).


The MEL is largely systems related:

PACS
Fuel Quantity
Pumps
Lights
Autopilot
Reverser
Anti-skid
Start valve
Generator

Basically, every ATA chapter has some things that can be inoperative and the aircraft remain safe for operation. These items being inoperative have a hard time limit, depending on the item. Most are limited to 10 calendar days, but a couple would be 3 day items, and some limited to flight hours.

Our NEF is generated within our engineering department, but is FAA approved.

Greetings from Airline Maintenance Land.

MEL = Minimum Equipment List (Something necessary for flight is inoperative, like an A/C pack, or an indicator light in the flight deck, but if you follow certain conditions listed in the MEL, flight may take place in spite of the broken equipment).

CDL = Configuration Deviation List (like a flap canoe; on some aircraft, a damaged flap canoe can be removed and flight may take place, albeit with a performance penalty from the increased drag.)

NEF = Non-Essential Furnishings (like a curtain separating first class from coach, these items are totally irrelevant to the operation of the airplane, but still must be documented.)

It's important to note that the final say still goes to the pilot; if he or she is made uncomfortable by the condition of the aircraft, even if things are legally deferred, then he or she may choose to reject the aircraft. Most often, that's unnecessary, because things have been done properly, and other layers of safety still are in place. But if a plane gets to the point where it has too many things MEL'd, a pilot will, eventually, say "enough is enough."

That said, a lot of people assume that we (maintenance) rarely ever fix anything, and simply go about our lives MEL'ing planes left and right. That's not really the case; while deferral is often the sensible and expedient thing to do (if it's safe and legal and ethical, there's nothing wrong with it), in many cases, we'll fix the issue if we have the necessary parts and equipment.

Two stories

I once had an aircraft that had multiple cockpit panel lights MEL'ed. I didn't think anything of it - it's just a few cockpit lights - flew the plane all day. plane flew great all day. .. until night time and it got dark. The instrument panel is the standard six-pack not glass. Turns out the cockpit panel lights were for the airspeed indicator lighting, altimeter lighting, RMI lighting, and vertical speed lighting, and panel backlighting. So now I had no instruments and was flying partial panel using only the Electronic Attitude Indicator and Electronic HSI. To complete the flight, had the FO hold a flashlight to illuminate the instrument panel so that we could see the panel. And you know what aviation flashlights are - certified dead twin D-cell battery holders

One day the captain I was flying with was irritated at the masking tape the mechanics used to tape the front cover of the aircraft maintenance logbook to the logbook. So after landing at the outstation, the captain wrote in the maintenance log. "Front cover of aircraft maintenance log needs replacement." He called it in and the maintenance supervisor asked him if he had already written it up. Yep. Poof the aircraft was grounded as there was no MEL relief for an "inoperative" maintenance log. The airline chartered an aircraft to fly a new maintenance binder out to the aircraft to "repair" the aircraft maintenance log.

Another deferral is a TAC item. Damage can be deferred ( perhaps with a temporary repair ) per a TAC. It's like an MEL. Also worn tires and brakes can be deferred per a TAC. This is at 1 major US carrier. Others probably have something similar. Also there is a FEA which requires engineering authorization.

CDL would be for stuff like this:

AirKevin wrote:

CDL would be for stuff like this:

Interestingly, some planes are allowed to fly with 1 winglet missing, but not 2, while other planes are allowed to fly with both winglets missing, but not with only 1 on the wings.

I’d add one more document:

DDPG - Dispatch Deviation Procedures Guide

Many MEL items have an “O” or an “M” indicating there are Operational or Maintenance procedures required to be followed to allow dispatch. This could include pulling CB’s, placarding inop systems, etc. - information found in the DDPG.

MEL’d items can add up to trouble however. On an acceptance flight for a VIP modified 757 for an oil rich sultan in Southeast Asia several major items were MEL’d by his crew because they were in a hurry to get the airplane home. We had to abort the flight after several other issues cropped up. After changing several parts with no improvement it was determined that during the modification when the master gold plated lavatory had been installed a screw had pierced the wire bundle controlling stabtrim, autopilot, outflow valve and other systems.

7BOEING7 wrote:

I’d add one more document:

DDPG - Dispatch Deviation Procedures Guide.

Is this same as a DMR entry (deferred maintenance record) eg : few fasteners or a faulty latch. These things are not specified in CDL or MEL. Sometimes can be found in AMM.

StereoTechque wrote:

7BOEING7 wrote:

I’d add one more document:

DDPG - Dispatch Deviation Procedures Guide.

Is this same as a DMR entry (deferred maintenance record) eg : few fasteners or a faulty latch. These things are not specified in CDL or MEL. Sometimes can be found in AMM.

No. The DDPG or Dispatch Maintenance Procedures (DMP) manual spells out the procedures required when an MEL is applied to an aircraft. Examples:

-If the thrust reverser is to be deferred as inoperative, the DMP provides the instructions on how to do it.
-If a PACK is to be rendered inoperative, the DMP will tells us what valves need to be locked out and what breakers to pull and collar.
-If a fuel quantity system is inop, the DMP will provide instructions on alternate means of determining the fuel quantity.

Woodreau wrote:

Two stories

I once had an aircraft that had multiple cockpit panel lights MEL'ed. I didn't think anything of it - it's just a few cockpit lights - flew the plane all day. plane flew great all day. .. until night time and it got dark. The instrument panel is the standard six-pack not glass. Turns out the cockpit panel lights were for the airspeed indicator lighting, altimeter lighting, RMI lighting, and vertical speed lighting, and panel backlighting. So now I had no instruments and was flying partial panel using only the Electronic Attitude Indicator and Electronic HSI. To complete the flight, had the FO hold a flashlight to illuminate the instrument panel so that we could see the panel. And you know what aviation flashlights are - certified dead twin D-cell battery holders

One day the captain I was flying with was irritated at the masking tape the mechanics used to tape the front cover of the aircraft maintenance logbook to the logbook. So after landing at the outstation, the captain wrote in the maintenance log. "Front cover of aircraft maintenance log needs replacement." He called it in and the maintenance supervisor asked him if he had already written it up. Yep. Poof the aircraft was grounded as there was no MEL relief for an "inoperative" maintenance log. The airline chartered an aircraft to fly a new maintenance binder out to the aircraft to "repair" the aircraft maintenance log.

With regards to the Aircraft Maintenance Log binder being damaged, I would immediately raise a non airworthiness related Deferred Defect to replace the binder at main base and get you off my station. Your company's MCC need to wise up a little (a lot) if they allowed an aircraft to be AOG due to such a minor/trivial issue!

FR8 is correct. DDPG is not a deferral authority. Acronyms vary. My airline calls this a MPM. Maintenance Procedures Manual. This gives deferral procedures as FR8 said. This is now incorporated in the MEL. The 737MAX has something like the DDPG. It is incorporated in the AMM.

packmedic wrote:

Here is the master Boeing 737 MEL document from the FAA. http://fsims.faa.gov/wdocs/mmel/b-737%20r54a.pdf

The actual MEL items can vary carrier to carrier, depending on what they've been approved for and what their aircraft are equipped with. Many MELs also come with some kind of deviation from standard procedures as well. A quick example which comes to mind is that 737NGs can have 1, 2, or 0 HUDs (at my carrier, only the captain has a HUD). If inop it can affect what kind of instrument approaches can be performed and the minimums for those approaches.

NEF may just be a galley table, or interior panel.

Off the top of my head I can't think of what would be on a CDL

For example, I've been on a 737-400 with MEL 21-15. Outflow valve had to be removed and we were limited to unpressurized flight at or below 10,000 feet. It was a short flight FAI-ANC and ended up becoming a ferry because ops didn't want to fly passengers on an unpressurized plane.

the CDL is the Configuration Deviation list. Which could be small doors or hatches missing or fairings like the Wing to body fairings missing at the wing leading edge root fairings or the ground air conditioning access door.

LAE320 wrote:

Woodreau wrote:

Two stories

I once had an aircraft that had multiple cockpit panel lights MEL'ed. I didn't think anything of it - it's just a few cockpit lights - flew the plane all day. plane flew great all day. .. until night time and it got dark. The instrument panel is the standard six-pack not glass. Turns out the cockpit panel lights were for the airspeed indicator lighting, altimeter lighting, RMI lighting, and vertical speed lighting, and panel backlighting. So now I had no instruments and was flying partial panel using only the Electronic Attitude Indicator and Electronic HSI. To complete the flight, had the FO hold a flashlight to illuminate the instrument panel so that we could see the panel. And you know what aviation flashlights are - certified dead twin D-cell battery holders

One day the captain I was flying with was irritated at the masking tape the mechanics used to tape the front cover of the aircraft maintenance logbook to the logbook. So after landing at the outstation, the captain wrote in the maintenance log. "Front cover of aircraft maintenance log needs replacement." He called it in and the maintenance supervisor asked him if he had already written it up. Yep. Poof the aircraft was grounded as there was no MEL relief for an "inoperative" maintenance log. The airline chartered an aircraft to fly a new maintenance binder out to the aircraft to "repair" the aircraft maintenance log.

With regards to the Aircraft Maintenance Log binder being damaged, I would immediately raise a non airworthiness related Deferred Defect to replace the binder at main base and get you off my station. Your company's MCC need to wise up a little (a lot) if they allowed an aircraft to be AOG due to such a minor/trivial issue!

United doesn't even have a log book on board so I doubt you would use that. We would put temp log book on board with all the required forms and a printout of the Latest Maintenance Release Document (MRD)a print out of the Defered Item List (DIL) and the Last 10 flight legs of history and they're good to go.
The pilots can electronically send and open log gripes to MX Control or? Call them in. we'll get them and deal with them when they arrive. It's not that big of a deal.
Especially since the aircraft requires a valid MRD before every departure.

Fabo wrote:

AirKevin wrote:

CDL would be for stuff like this:

Interestingly, some planes are allowed to fly with 1 winglet missing, but not 2, while other planes are allowed to fly with both winglets missing, but not with only 1 on the wings.

Wonder if it's a difference between blended winglets like on the 737, and standard winglets like on the 747.