Why are logo lights included in the (M)MEL?

[Big Bad D]

Can anyone help explain the reason why aircraft tail logo lights are included in an (M)MEL? Navigation and landing lights and strobes must be included of course; but why the logo lights, which, as far as I understand, serve no safety purpose nor are required by aircraft design or operational regulations?

[FlightDetent]

Just a thought: Because, if they were not, dispatch would be impossible?

A320 MMEL is D, what's yours type and rectification interval?

[Big Bad D]

Thanks FlightDetent for your response. My question related to A330 and it too is Category D. But the origin of my question and my knowledge of the MMEL is theoretical, as I am involved in aircraft design rather than maintenance and aircraft dispatch.

The MMEL preface says that "it lists the equipment, components, systems or functions, for which dispatch conditions apply". It also states that "The MMEL does not include... items which do not affect the airworthiness of the aircraft..." followed by a note "Thus all items which are related to the airworthiness of the aircraft and not included in the list are automatically required to be operative for each flight".

So my understanding was that if an item is not listed and the item is not airworthiness related then there is no minimum number or condition needed for dispatch. And hence my surprise to see that the logo light was even included in the MMEL at all.

Perhaps I misunderstand the concept and use of the MMEL? In which case I am very willing to become better educated!

[Swedish Steve]

If Logo lights were not in the MEL, some stroppy pilot could sit on the ramp with inoperative logo lights and claim that they were required for flight as they are an aid to aircraft visibility.

[FlightDetent]

If I get it right. The LL provision in MMEL indicates it is an airworthiness item, why is it so, especially given the fact that it is an optional equipment? Or, are there any other benefits / considerations why have this specific item covered under MMEL rules?

Well, personally, I have no clue.

FD (the un-real)

MMEL Preamble

For the sake of brevity, the MEL does not include obviously required items such as wings, control surfaces, engines, landing gear, etc... or items which do not affect the airworthiness of the aircraft such as galley
equipment, entertainment systems, passenger convenience items, etc...
THUS, ALL ITEMS WHICH ARE RELATED TO THE AIRWORTHINESS OF THE AIRCRAFT AND NOT INCLUDED IN THE LIST ARE AUTOMATICALLY REQUIRED TO BE OPERATIVE FOR EACH FLIGHT.

Or on a second tought: perhaps it is connected to the fact that unlike IFE it cannot be turned off and the manufacturer thinks it is not wise to allow indefinite operation of faulty unit attached to circuitry with other, required elements. ?

[Flyit Pointit Sortit]

ATC: "After the landing xxx airways aircraft" or, as in Paris, "give way to the air france"

It could be that at night, it is a little more difficult to to see the airline if the logo lights are u/s.

Or I could be completely wrong.

[Capt Claret]

... some stroppy pilot could sit on the ramp with inoperative logo lights ...

And somewhere, some stroppy regulator would berate a pilot for flying without operative logo lights and no MEL relief.

[Big Bad D]

FlightDetent, your "second thought" is indeed almost exactly the question I have received from an airline, and which has resulted in this thread.

The airline wants to disable the logo lights indefinitely as a maintenance saving. However the MMEL effectively stops them from leaving the system inoperative for more than 120 days. I agree that leaving a system unserviceable indefinitely is not a good policy and, yes, perhaps this is a factor for inclusion of logo lights in the MMEL.

Thanks for all the feedback.

[glhcarl]

Can anyone help explain the reason why aircraft tail logo lights are included in an (M)MEL?

I think its the case of "if you have it, it must work".

In other words if you want to permanently disable the "logo lights" you have to have a service bulletin that would: remover the switch, disconnect the wiring and cover over the lens. Not just let the bulb burn out and ignore it forever.

ATC: "After the landing xxx airways aircraft" or, as in Paris, "give way to the air france"

It could be that at night, it is a little more difficult to to see the airline if the logo lights are u/s.

Or I could be completely wrong.

Highly unlikely as many airlines don't have "logo lights".

[Pugilistic Animus]

What ever would Emirates do?

[mnttech]

The airline wants to disable the logo lights indefinitely as a maintenance saving. However the MMEL effectively stops them from leaving the system inoperative for more than 120 days.

Then have them correctly removed by either an STC, approved EO, or field approval. As stated earlier, if it is installed, it must work or the aircraft does not meet the design data. So in the US, it is one of the above methods to change the design data. I know that a field approval is not available out side the US, but an approved Engineering Order, or and STC would work I believe. The removal could be as simple as removing the CB's and switches, or something along those lines. Or the operator could have their MEL changed (by the certification people) to delete them.

[Big Bad D]

In line with what many people have commented, the manufacturer's response is that the logo lights are included in the MMEL in order to avoid flight crew incorrectly flagging them if failed as a no-go item.

I fully agree, mnttech, that the correct solution would be to raise a modification SB to remove or disable the logo lights, and that is what is being proposed to the airline concerned. Although there is a small added complication that such a modification would require a change to the MMEL as it currently identifies that all aircraft must be fitted and operated with logo lights.

[FlightDetent]

No further added value from my side to the above drawn conclusions.

Originally Posted by Big Bad D

such a modification would require a change to the MMEL as it currently identifies that all aircraft must be fitted and operated with logo lights.

I'm convinced to have seen operator's fleet configuration that do not have logo light installed. Perhaps the desired MMEL version may not be beyond reach after all?

[mnttech]

MMEL vs MEL

While it's a very small point, the MMEL is the Master Min Equip List, in the US it's put out by the FAA, I'm not sure about other countries. Then each operator must take it and modify it for their use, and it becomes the MEL. Operator A may require the Logo lights, while operator B does not.

[adverse-bump]

Its my understanding, that if something ISNT in the MEL, then it is a stopper. regardless of what it is.

[Conan The Barber]

Originally Posted by adverse-bump

Its my understanding, that if something ISNT in the MEL, then it is a stopper. regardless of what it is.

Perhaps that's why logo lights are in the MEL. To guard against people who haven't bothered to read their MEL's preamble and ground aircraft for no reason other than ignorance.

[glhcarl]

While it's a very small point, the MMEL is the Master Min Equip List, in the US it's put out by the FAA, I'm not sure about other countries. Then each operator must take it and modify it for their use, and it becomes the MEL. Operator A may require the Logo lights, while operator B does not.

I think you will find that an operator can create their own MEL: by adding items to the MMEL. They can not remove items from the MMEL.

[chuzwuza]

As stated above the MMEL is the master. It sets the minimum equiptment required for dispatch iaw the a/c manufacturer. The MEL is a document produced by the individual operator which is fine tuned to include their own proceedures. The MEL is always a more strict document than the MMEL.

Any item/system listed in the MEL must be maintained iaw the MEL (i.e if logo lts are 120days, you fix them in 120 days or earlier).

As for the original question regarding logo lts, if installed, they must work iaw mel time limitations. The main purpose for them is for ease of on ground identification. I accept that not all a/c have the system installed but it was considered to be an extra benefit. Anybody remember when BA rolled out the new multicoloured paint scheme on the vert stab of their a/c? I heard from my cousin (an atc controller at LGW) that this alone caused great confusion. When requesting airline xyz to follow the BA 767 the reply was quite frequently "which one is that" or words to that effect.

[john_tullamarine]

Some points of confusion I suspect ..

(a) the aim is to maintain the risk levels of the original Type Certification.

(b) this means ALL the design standards, many of which are not known to the typical flyer, have to be included in (M)MEL assessments

(c) if widget A (not being in the (M)MEL) is broken, then the (M)MEL (or defacto) stakeholders have to assess what restrictions, if any, are required to permit ongoing operations at a similar to original risk level. The MMEL provides guidance to the operator producing the MEL, the MEL provides prescriptive minimum guidance standards to the operating flightcrew and maintainers. In some jurisdictions (Australia for instance, with CASA's GMEL system) the regulator gets involved at the MEL design level to simplify the whole exercise for everyone.

(d) risk assessment involves probability and consequence of occurrence, and period of exposure to the risk .. hence the time limits on MEL items

(e) items which do not affect the airworthiness of the aircraft...

the problem here is that the typical flyer is not well-placed to assess this question, other than for day to day operational considerations .. refer (b)

(f) the MMEL is not exhaustive in that only those items considered "useful" are likely to be included. There is no reason why an operator cannot present an argument to the relevant regulator for additional or varied permissions when considering the (M)MEL

[Desk Jockey]

Relamping logo lights isn't everyones idea of fun but I always call them to be repaired on the ramp because it's hard to miss something the side of a house all lit up.

As far as leaving the system redundant is concerned I would expect a blank would be required because occasionally the lenses break up and if the system is inop it would be a while before it was discovered.