MEL's

[aqk]

Just wondering what everyone else's experiences are with MELs.

When our MELs were implemented it was explained to us that if it is not in the MEL it is not deferrable. However, since then, there have been many times when a non-airworthiness related item was broken, but was not in the MEL. So by our what was explained to me, the plane should be grounded.

The way I thought MELs worked was that, if it is a non-airworthiness related issue, it could simply be deferred, however if it was an airworthiness issue, or even borderline, that the MEL would guide you, and that you may still be able to fly but possibly with restrictions, or only for 3 days, or whatever.

So I guess the question for me is, has the MEL been explained to me slightly improperly or can you defer non-airworthiness items outside of the MEL?

What has everyone else been told/experienced?

[square]

Last time I checked the MEL to see if I could fly without operable flaps, I couldn't even find flaps in there, let alone a flap motor. So apparently you can remove the flaps and you're good to go.

[KISS_MY_TCAS]

Dunno what to say about square's post....

Non airworthiness items (like a snag that says a cabin tray table is broken, carpet is torn, etc.) can be deferred outside the MEL, usually with the company's MCM as a guide. Airworthiness items such as the flaps (as pointed out in square's post) are cut and dried in the MEL, either they work or they don't....if in the MEL press on, if not you are grounded.

[square]

if in the MEL press on, if not you are grounded.

Isn't it the other way around? I thought the MEL was supposed to be a list of the, well, minimum equipment you have to have working, not a list of stuff you can defer.

[KISS_MY_TCAS]

if in the MEL press on, if not you are grounded.

Isn't it the other way around? I thought the MEL was supposed to be a list of the, well, minimum equipment you have to have working, not a list of stuff you can defer.

Precisely, it is the minimum equipment list, but allows for flight with a system or component inoperative. If it is not in the MEL and it is an airworthiness item, the plane does not fly if it is inop. Exactly why the MEL exists. For example, you will not find a wing in any MEL. If you feel safe flying with one missing, try and legally defer it. You won't find it in the MEL.

[CD]

The preamble to the MEL generally provides a good description for the use of the document and what it contains. An example of a preamble can be found here:

TP 9155 - Appendix F - Transport Canada Master Minimum Equipment List (Aircraft Type)
TP 14408 - Transport Canada Civil Aviation Guidelines: Maintenance Control Manuals

Preambles generally include the following information:

The approved MMEL includes those items of equipment related to airworthiness and operating regulations and other items of equipment Transport Canada finds may be inoperative and yet maintain the required level of safety by applying appropriate conditions and limitations; it does not contain obviously required items such as wings, flaps, and rudders. The MMEL is the basis for development of individual operator MELs which take into consideration the operator's particular aircraft equipment configuration and operational conditions. Operator MELs, for administrative control, may include items not contained in the MMEL; however, relief for administrative control items must be approved. An operator's MEL may differ in format from the MMEL, but cannot be less restrictive than the MMEL. The individual operator's MEL, when approved, permits operation of the aircraft with inoperative equipment.

[Troubleshot]

Also some operators utilize a CDL-Component Deviation List. This list is useful for removing damaged components that may effect performance but not airworthiness (ie. fairings, seals,etc...) usually there is some sort speed penalty or MTOW reduction though. Very useful manual indeed.

[ruddersup?]

Doesn't an MEL allow you to deviate from the type certificate? Anything not on the t.c. can be deferred?

[TwinOtterLover]

type certificate does not really have anything to do with an MEL, its pretty much just a cut and dry case, if its an airworthiness item and its not in the MEL you dont fly, if it is in the MEL then you can fly for a bit but you better fix it soon.

[twnotter]

I agree with twinotterlover, if it's not in the MEL then you can't defer. Some AMO's have a system to track non airworthiness defects, such as cosmetic items, to be fixed at a convenient time. This system of course has to be in the TC approved MCM.

[square]

So since there's nothing about flaps in the MEL, it is non-deferrable if they aren't working? Doesn't seem justified though because the A/C is approved for flapless takeoffs and landings.

[TwinOtterLover]

check the MMEL, remember your MEL is approved for each individual company by TC and your types of operations is a large factor in what is approved but the aircraft manufacturer will have an MMEL which is the main guideline for an MEL and it could have flaps in there even though you cannot defer according to an MMEL it can help in some grey areas and allow your company to adjust its MEL

[square]

Oh shit I didnt even know there were company-specific MEL's, I guess I should check that one first..

[george sugar]

Edited in deference to 29 ford's comments below, and in the interest of accuracy.

The MEL never, ever, has any effect on the type certificate for your aircraft. You can under no circumstances go outside of the approved limitations contained there. If an MEL is required (e.g. 705 carriers), then a company must develop an MEL for their aircraft and not merely adopt the MMEL. If one is not required, then all installed equipment and systems that were used in the type certification of the aircraft, and are contained in the CARs as minimum for intended use, must be operative.

The MMEL has nothing to do with the day-to-day operation in your company. It cannot be used for relief in dispatching your aircraft, so on the line it may as well not exist and don't look at it. In no case may the company MEL be less restrictive than the manufacturer's MMEL, nor can the MMEL be used as an MEL; each operator must develop their own and have it approved by Transport Canada. And the Maintenance Control Manual (MCM) has nothing to do with you as a pilot, either. Your limiting documents are the Company Operations Manual and Minimum Equipment List.

The company MEL may be adjusted to more closely conform with the MMEL, but only after it is approved by TC.

By definition all equipment and/or systems on an aircraft are an airworthiness item of one form or another, depending on what the aircraft is being used for. Passenger safety items and cabin furnishings can be no less restrictive than engine components, in that you cannot dispatch for a particular operation if there is no relief . A torn carpet is not an issue unless it poses an obstruction, but something like a tray table or inoperative recline would have to be secured up to ensure access for evacuation. Slides and inoperative exits may require that you restrict the number of passengers on board.

If the inoperative equipment and/or system is not addressed in the MEL, it is a no-go item and must be operative prior to dispatch. If the inoperative item is addressed in the MEL, there are often operational restrictions or cabin restrictions associated.

The CDL (Configuration, not Component as Troubleshot suggests) must be published along with the MEL, and in no way substitutes or replaces the MEL. It is as Troubleshot suggests for external items which may affect performance. The missing wing is obviously not mentioned in the CDL.

The best advice comes from CD, read and understand the preamble for your particular MEL, and compare it to TP 9155 http://www.tc.gc.ca/CivilAviation/publi ... endixF.htm.

And I might add that if your company uses an MEL, then the CARs/CASS requires that you receive sufficient training so that you have no question in your mind as to its proper use.

[29 ford]

Here's my take on it:

Most company's have a way of tracking non airworthy defects usually called DMI's. So lets say a Circuit Breaker panel identifier on a 727 freighter has fallen off and gone missing. First check the MEL even though I doubt it would be there since we may want to know what the CB's are for in case one pops or it could possibly have to be pulled in flight for some reason but check it anyways because you never know. So is it a no go? Depends, probably all the CB's in the row were for galley equipment that is no longer used and are pulled and collared. In this instance I would have no issue putting it on a DMI even though it is not in the MEL, or if the CB's were used you could probably use a P-Touch and make a temp identifier until you got a new one and DMI it that way. So basically if it's not in the MEL (dare I say it) you have to use "Common sense".

[29 ford]

George I have to disagree somewhat when you say if the inoperative component is not in the MEL it is a no go. Lets say Captain Jelly fish calls from one of those shiny new 767's and says the lav smoke detector won't test and it's not in the MEL so I'm not taking it, I'm pretty sure Maintenance Control is going to say make sure you take a piss before you leave because the whole lav is going on MEL. Using the MEL to your advantage takes experience and I'm sure Transport wouldn't have an issue with the above example.

[george sugar]

A lav smoke detector does not cause the aircraft to be physically unflyable, and if the smoke detector is in the MEL then there is usually relief provided in the form of blocking off the lav. However, if a component that was a part of the type certification of the aircraft (like a lav smoke detector) is not listed in the MEL, there is no relief provided and it must be operative. Maintenance control cannot arbitrarily add items to the MEL on the spot, and Transport most certainly would take issue since an inoperative component that is not provided relief in the MEL renders the C of A invalid on a 705 aircraft or any aircraft that has an approved MEL. This is why the MEL must be as comprehensive as possible to provide the greatest flexibility, but it must be approved in advance.

[29 ford]

OK, so a flow control valve craps out. A flow control valve is a component and is not listed in the MEL. Can I MEL the Pack?

[dashx]

so a flow control valve craps out. A flow control valve is a component and is not listed in the MEL. Can I MEL

No.

It has to be in the MEL.

MEL recognizes redundancy of some systems and allows you to operate with one (or more) components not working.

Example.

Dash 8 100 has two pressure regulator and shut off valves (one in each nacelle) while the Dash 8 200 has one pressure regulating valve in the rear. Neither one shows up in the MMEL.

Dash 7 has four flow control valves. MEL allows for deferral of a flow control valve.

[29 ford]

Were talking 2 different things, my question was to George in respect to a 727. If the flow control valve on a 727 didn't work all it would do is make the air conditioning pack inoperative. In respect to the Dash 8 and Dash 7 you are referring to engine air.

[itismedd]

I would have to agree with 29 ford . If the pack valve crapped out and it wasnt in the MEL, that Aircraft will be flying at 25000 with one pack. Provided of course that a pack was in the MEL.

[george sugar]

I cannot definitively reply without consulting the MEL itself; don't have it quite memorized as yet, and even then. Indirectly, what it is telling you is that if you want to use the pack, the flow control valve must be working. The guidance for such things is provided in the Dispatch Deviation Guide from Boeing, and is used in conjunction with the MMEL in developing the company MEL. In this particular instance, I would suspect that an inoperative component in a sub-system would be considered to render the entire sub-system inoperative, and if the maintenance procedures are followed to secure the system, and the operational procedures are followed in the subsequent operation of the aircraft, there would be relief under the MEL using the inoperative pack portion, provided there is relief for one pack inop, as you say. If the MEL is not sufficiently clear in such instances, then this should be brought to the attention of the person responsible for the MEL for revision. The MEL is a constantly evolving document which should be continuously reviewed for accuracy and clarity, and to reflect the particular operations being undertaken; the best people to pass such information on are the flight crews and engineers that use the MEL every day.

[29 ford]

Exactly, all I was saying is the word "component" I don't think is correct. I would use the word "system". If a crew said the ADF control head digits were unreadable at night your not going to find ADF control head in the MEL but you may find ADF system. Alot of the time when you MEL stuff you may not even know which component in the system is causing the defect so if you MEL the system you have covered all the components in that system.

[dashx]

If the flow control valve on a 727 didn't work all it would do is make the air conditioning pack inoperative.

Dash 7 and 8 have a ram air system:

If the air conditioning pack should fail, ram air pressure will cause the check valve
to open and let ram air enter the conditioned air supply duct. The ram air now
ventilates the cabin and flight compartment. Cabin and flight compartment
ventilation can be increased by slightly opening the safety outflow valve.

I have never used the phrase engine air. Its always been bleed air in my books:

Bleed air for system operation comes from each engine’s high and low pressure
ports

And the flow control valves are designed to fail safe in the open position.

I was only using the 7 and 8 as examples for the MEL.

Sorry.

[george sugar]

Yes 29 Ford, I will gracefully concede the point; "component" is perhaps too specific or may be misleading, and I have edited my original post above. The word Transport chooses is "equipment", which can be taken more generally. But absolutely, the MEL can apply to a single part, or a collection of parts (system). And the finer the detail, the better the guidance is. In your example, it may be more clear if the flow control valve was listed in the MEL, and the comments stated that relief is allowed provided the associated pack is considered inop with the suitable MEL reference to the pack itself. This way there would be no doubt on how to proceed. Your ADF example is of this type as well, but there are practical limits to how much detail one can provide for all of the various sub-systems.