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FAA Emergency Airworthiness Directive apply to AC's 777-300ER GE90-115B engines?

FAA Emergency Airworthiness Directive apply to AC's 777-300ER GE90-115B engines?

Old Oct 24, 2019, 11:45 am
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FAA Emergency Airworthiness Directive apply to AC's 777-300ER GE90-115B engines?

FAA issued this AD after the recent TG engine failure at ZRH. We know AC has the same engines on the 777-300ERs. But obviously some of us don't know if AC has the same part # listed in the AD. Either way, what does AC do when this type of AD is issued?


http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/936cdd0f9b2d29ae8625849c006dc9cd/$FILE/2019-21-51_Emergency.pdf


QUOTE:





https://www.aircanada.com/ca/en/aco/...ard/fleet.html




Last edited by 24left; Oct 24, 2019 at 5:42 pm
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Old Oct 24, 2019, 5:03 pm
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The short answer is that AC is legally responsible to follow the exact T&Cs set forth in this AD. Below I have set forth the reasons why AC has to follow it.


The impact of an AD depends on the condition set forth in the AD. A few background notes:

1) In order for an aircraft to fly, it must be in possession of a valid Air Worthiness Certificate. As summarized nicely on Wikipedia:

A certificate of airworthiness (CofA), or an airworthiness certificate, is issued for an aircraft by the national aviation authority in the state in which the aircraft is registered. The airworthiness certificate attests that the aircraft is airworthy insofar as the aircraft conforms to its type design. Each airworthiness certificate is issued in one of a number of different categories. A certificate of airworthiness is issued when the aircraft is registered in the name of the owner. Thereafter, a yearly currency fee is payable to renew the Certificate of Airworthiness. If this fee is not paid when due, the certificate expires and the owner must apply again for this certificate to be issued. The Certificate of Airworthiness can only be issued when a certificate of release to service from the maintenance facility declares that the maintenance due has been carried out and the aircraft is then certified as being airworthy.
2) Also from Wikipedia:
An airworthiness directive (commonly abbreviated as AD) is a notification to owners and operators of certified aircraft that a known safety deficiency with a particular model of aircraft, engine, avionics or other system exists and must be corrected. If a certified aircraft has outstanding airworthiness directives that have not been complied with, the aircraft is not considered airworthy. Thus, it is mandatory for an aircraft operator to comply with an AD.
To summarize the two points above: if the conditions of an AD are not met, the aircraft is not considered airworthy. In this case, in order for Boeing 777-300ERs under the FAA's jurisdiction to remain airworthy, the operators are required to:
Within 25 flight cycles after the effective date of this AD, remove from service the Interstage Seal, part number 2505M72P01 with serial numbers GWN0TCL3, NCE062LD, NCE254LC, NCE314KU, NCE374LB, NCE527KT, NCE777LD, or NCE994KW.
.

Even though this AD is issued by the FAA for American registered aircraft, in Air Canada's case they are also required to comply with this AD as Canadian Aviation Regulations 605.84 "recognizes the mandatory status of foreign ADs and equivalent notices issued by the aviation authority that has jurisdiction over the type design of the aeronautical product". This means that if the aviation authority has jurisdiction over that specific type design, then the AD must be followed in Canada. In even simpler terms, if the US puts and AD on a US product, Canadian registered aircraft have to follow it. If the US puts an AD on a non-US product, then Canadian registered aircraft do not have to follow it. The FAA is responsible for the type design of the Boeing 777-300ER, therefore the AD is mandatory for Canadian registered Boeing 777-300ERs, and AC must comply with the AD before their aircraft hit 25 cycles after the receipt of this AD.
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Old Oct 24, 2019, 5:28 pm
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@marchelli

Thanks for this !!!!
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Old Oct 24, 2019, 6:09 pm
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This is interesting.

Is anyone with the necessary experience able to say how long a repair like this might take? It it's just a seal it's probably not that long, but I'm curious. Scheduled to fly a 777-300 in 3 days. Not even remotely concerned about my safety: more concerned about an aircraft swap.
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Old Oct 24, 2019, 6:15 pm
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Airworthiness Directives are routinely sent to operators of commercial aircraft, and could relate to any component of any airplane. This is not the first nor the thousandth AD received by Air Canada. As explained above, the operator must comply with the AD within the stipulated timeframe/cycles, or else the plane doesn't fly.

I don't know how long it takes to replace an interstage seal, or even if AC is affected by this AD, but this is the sort of thing done overnight when the planes are towed into the hangars for routine maintenance. I imagine the only likely disruption is possible revised scheduling & prioritization of various fins by the maintenance planners.

Originally Posted by WaytoomuchEurope
Scheduled to fly a 777-300 in 3 days.

It's unlikely any of the 777s will reach half the number of cycles within 3 days.
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Old Oct 24, 2019, 6:24 pm
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Originally Posted by CZAMFlyer
even if AC is affected by this AD
I knew I forgot to mention something! It may also be the case, that none of the AC 777-300ERs have the effected parts.

I agree with CZAMFlyer , from what I've read, I don't think it will have a major impact on fleet operation.
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Old Oct 24, 2019, 6:26 pm
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Originally Posted by CZAMFlyer
Airworthiness Directives are routinely sent to operators of commercial aircraft, and could relate to any component of any airplane. This is not the first nor the thousandth AD received by Air Canada. As explained above, the operator must comply with the AD within the stipulated timeframe/cycles, or else the plane doesn't fly.

I don't know how long it takes to replace an interstage seal, or even if AC is affected by this AD, but this is the sort of thing done overnight when the planes are towed into the hangars for routine maintenance. I imagine the only likely disruption is possible revised scheduling & prioritization of various fins by the maintenance planners.

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It's unlikely any of the 777s will reach half the number of cycles within 3 days.

Thanks for the response. Agreed about the cycles, though nothing would stop them from doing the swaps early.

Having said that, I'm hanging on your "overnight during routine maintenance". All in all a very minor issue if the aircraft were to be swapped - I was just curious. Again, thanks for the response.
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Old Oct 24, 2019, 6:32 pm
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It appears this particular directive applies to only those 8 specific sub-assemblies with the noted serial numbers.

My educated guess would be that there was a bad batch of some unserialized component (think a bolt or the literal unobtanium rubber seal) that they identified, but could only attach to a window of use, and X months of thingy use in a repair bay means touching those 8 assemblies.

All normal aviation things. Nothing to see here.
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Old Oct 24, 2019, 6:35 pm
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WaytoomuchEurope, although I spent a good portion of today buried within the bowels of a large four-engined jet today, I am not a maintenance engineer, so please don't place any degree of faith in my prognosticatory musings. I consulted my good friend Mr Google, and an interstage seal seems to be wedged between two major, yet very much internal components of a turbine engine. However, with the necessary staff & tooling, I've seen engines wholesale swapped, or torn apart and put back together in remarkably short periods of time.
These are the workhorses of AC's most lucrative routes and the airline is already, as we all know, capacity-constrained so I imagine if there's a critical AD to address, it will be accomplished with all hands on deck.

Originally Posted by RangerNS
All normal aviation things. Nothing to see here.

Bingo.
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Old Oct 24, 2019, 6:46 pm
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Originally Posted by RangerNS
I...All normal aviation things. Nothing to see here.
Maybe not, but still worth asking the question.
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