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Specified Data

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I attended an avionics workshop recently hosted by Transport Canada in co-operation with the Aircraft Electronics Association (AEA).


The workshop was open to industry delegates and avionics maintenance people including line and shop specialists.


During the discussions, a great deal of time was spent talking about “specified data” and the appropriate use of it. After listening to several statements, I was convinced that the understanding of the definition of “specified data” was quite varied. We all know that major repairs and modifications must be performed in accordance with “approved” or “specified” data but do we all understand what constitutes “specified” data?


Many attendees of the workshop regarded avionics installation manuals as “specified” data. Others regarded avionics manufacturer’s service bulletins as specified data. For example, some felt that if Rockwell Collins issued a service bulletin that changes a VHF COM to operate with 8.33 KHz spacing, it is appropriate to replace the existing 25 KHz COM with the new upgraded one modified by service bulletin.


I agree that for the purposes of modifying the COM (an aeronautical product) the avionics’ manufacturer’s service bulletin is considered “specified” data, but not for installation on the aircraft.


The airworthiness manual defines specified data as:


“specified data” - is information contained in authoritative documents which, although not approved by the Minister, has been specified by the Minister as appropriate for the purpose of major modifications and major repairs, in conformity with section 571.06 of the CARs. The following are examples of specified data:

(amended 2000/12/01; previous version)

(a) drawings or methods described or referenced in Airworthiness Directives;

(B) data issued by the manufacturer or type certificate holder of the aircraft, component or appliance, such as modification orders, service bulletins, or engineering orders, which include a statement of approval by the applicable regulatory authority or a delegated representative of such an authority. Where the data issued by the aircraft manufacturer are incompatible with those of the component or appliance manufacturer, the data of the aircraft manufacturer shall prevail;

© manufacturer’s Structural Repair Manuals;

(d) FAA Advisory Circulars AC 43.13-1 and AC 43.13-2, subject to the following conditions:

(i) the aircraft is a small aircraft, and the alteration does not affect dynamic components, rotor blades, structure that is subject to pressurization loads, or the primary structure of a rotorcraft;

(ii) the alteration does not affect an existing limitation (including the information contained on mandatory placards) or change any data contained in the approved sections of the Aircraft Flight Manual, or equivalent;

(iii) the data are appropriate to the product being altered, and are directly applicable to the alteration being made; and,

(iv) the data are not contrary to the aircraft manufacturer’s data.


Personally, I feel the acid test for determining if something is possibly “specified” data is if it somehow indicates that the certification basis of the aircraft has been considered. So, I don’t think avionics installation manuals or avionics manufacturers service bulletins meet the requirements of the definition of “specified” data for modification of aircraft.

What do others consider adequate “approved” or “specified” data?

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I think its another round about way for TC to escape further liability, A sane person would automatically assume that “Specified Data and Approved Data” are one and the same, and conversely approved data is specified data!! I think it goes back to the old Blind Encoder scenario, where it was hotley debated to include it as a minor repair/mod by the workforce. While TC struggled to class it a major mod excluding the fee. So it was written -- if lacking approved data, a engineering approval was needed. Which resulted in too much work for the RAE’s. They in turn suggested major avionic repairs could be done using “specified data“.


What’s the frikin difference!!!

Sounds like a E&I manual comeback to me!!


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God louie, we could only wish things went back to the E+I days... At least then you could understand what they were trying to say... :rolleyes:


As for #####s original question, I'd say, anything TC will accept is good for me.. Depending on who you are dealing with, the line changes accordingly...

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TC M&M really should get it's collective act together. For instance, the installation of a set of shoulder harness in a 50 plus year old tube and rag aircraft has the approved TC method of attachment in the appropriate manual...the number escapes me. looking at the drawing, it seems very straightforward to me, but the local M&M gurus insist on a DAR doing his calculatiuons for an approval...why when TC has it all laid out. So you spend $85.00 per hour having some guy who has never worked on any type of aircraft doing the math then handing you a big fat bill at the end of the exercise.


You are only too right Twotter...give us back the old E&I manual...written by sane people who know about aircraft

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Just out of curiosity OFD, what were the particulars? Was the harness TSO'd? You can use AC 43.13 (specified data for small unpressurized aircraft) to sign off a shoulder harness if the assembly is approved (TSO'd) with no DAR involvment.


By the way, I wouldn't be too quick to state that all DARs have "never worked on any type of aircraft". Its just not an accurate statement.


E and I manual? That thing was a dog's breakfast in my opinion. And it didn't take away the requirement of engineering involvment in modifications anyway, which is what this discussion is about. You still may have needed DAR or TC engineering involvement with your shoulder harness problem.


It is rather obvious by the responses, that many aren't familiar with the particular AWM section that describes the types of data used for modifications. And its nothing new. That section of the AWM has been around since the CARs were introduced, and it just replaces policy that existed in the E and I days.


Specified data is just data that is not contained in an LSTC, STC or RDC (approved data) but can be used to approve major repairs or modifications because it was developed in the context of the aircraft certification basis.


In simple language, an STC,LSTC or RDC essentially declares that a mod or repair meets the requirements of the type design contained on the TC (type certificate), so other data used to approve mods must also be tied to the TC.


Specified data includes SRMs and Service Bulletins because those documents can be traced to the TC.


They also include AC-43.13 for certain mods on light aircraft because many small airplanes don't have an SRM of their own and the modifications in AC 43.13 are well suited for such aircraft.


But...a GPS installation manual for instance is NOT considered specified data, because it wasn't written with any particular aircraft's certification basis in mind and there is no corresponding statement in these sorts of manuals that declares it meets any airworthiness standard. Which is essentially what a DAR or RAE does with an LSTC/STC/RDC.


The main reason I raised this question, was that it appears that industry and TC M and M alike have quite a diverse view of what defines specified data as twotter points out, and it seems there is a fundamental lack of understanding of AWM 571 here.


I wonder what a quick review of mod reporting forms at the local M&M department would find? How many mods out there are being done with questionable data?

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At the risk of being labeled a missfit in aviation and an habitual moaner on this site I am going to comment on the help your local M&M office can provide.


Remember that Cessna 150 that I had leased to a flight school and that TC Inspector found the propellor problem on a couple of years ago?


Well I finally have the problem solved and I can now sell it.


I was unsucessful in getting an LSTC approval here in Lotus Land for several reasons such as I would have been dead and buried before the paper work would have been finished.


I finally found a DAR with dual licenses who said if you want your airplane flying with that prop I can get an STC in the US and sell you a copy.


So guess what three weeks later I had an STC for the prop at about !/4 the cost of dealing in Canada.


I had even asked the Regional Director General to interceed on my behalf to get M&M to move on the problem I had explained that the propellor was identical to the propellor that was listed in the Cessna Data sheet for my airplane, only the stamp was different..... one was stamped HCM the other was Stamped OCM...


The US officials noted that the only difference in the two propellors ( confirmed by McCauley. ) was the stamp and presto a STC was issued.



Sorry for ranting again but I thought it might be relevant to this discussion.


By the way one DAR quoted me around $2000.00 to get a LSTC approved, he explained that TC would need to have tests performed such as noise abatement flight tests performed.......


Anyhow I can now sell the thing.


Chas W. ...Dr. of Divinity

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I finally found a DAR with dual licenses..


There is no such thing. For one, its a delegation, not a license. And the FAA won't go for it. I know...I've tried. You have to be a US resident and have a permanent address. As a delegate you are acting directly on behalf of the airworthiness authority. In essence you "ARE" the FAA or TC. The FAA doesn't want to be directly represented by a Canadian in Canada. You must also have a minimum number of projects to submit or your delegation gets deactivated. Essentially, they tell you right to your face "no".


Furthermore, if done properly, when an FAA DER uses a Canadian registered test article for a mod, there is a blizzard of paperwork involved. Plus a minimum 30 days to process an FAA STC that starts on the date of submission that the FAA imposes, makes the issue of the prop STC sound a little shakey in the 3 week time period.


A Canadian DAR can submit a data package to the FAA through the proper channels and get an FAA STC in roughly the same time period. I assume that is what your "dual" DAR did.


And if I recall, the 2 props aren't identical. Isn't one heavier? And wasn't there a slightly different RPM limitation? And a different backplate or something?


And...I'm not defending the DAR that quoted you $2K, but the vast majority of mod packages I see coming out of the US are crap. They don't even follow their own airworthiness standards down there. Of course when the STC is on a small US state of design airplane, it doesn't need to pass the scrutiny of TC.


It isn't directly apparent that the mods are unsafe...but then you have to ask yourself why so many US aircraft manufacturers go broke when they are mired in liability litigation.

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I will advise the FAA that they forgot to check with you and issued an STC that may be questionable.


I hope the FAA will however recognize that the home address of the DAR I used to be still part of the USA... the State of Washington....but just to make sure should I ask for his birth certificate or passport?


##### why do you have to be such an [edited]?


Chas W. Not so reverend this time...

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I hope the FAA will however recognize that the home address of the DAR I used to be still part of the USA... the State of Washington....but just to make sure should I ask for his birth certificate or passport?


Are we talking "DAR" or "DER"? An FAA DAR is kind of like an MDM here. A DER is the equivalent to a Canadian DAR.


If you don't use the proper terms, its hard to establish just how relevant and authoritative your posts are. I was merely trying to avoid further confusion which is the fundamental issue in this thread.


##### why do you have to be such an [edited]


I refuse to respond to the above statement contained in Charles' post as I feel it violates the intent, spirit, and rules of the CAAviation forum.

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