A Guide to Using the FAA PMA Data
Introduction
The Federal Aviation Administration (FAA) compiles and publishes Parts
Manufacturer Authority (PMA) data. A PMA is required under FAR 21.303(a) in
order to manufacture and market aeronautical products for installation on type
certificated items. This information is free and may be obtained either by
interaction with the online Regulatory and Guidance Library (RGL) database or
download from the FAA website.
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgpma.nsf/MainFrame?OpenFrameSet
This article is a guide to using that information with some tricks and
techniques to assist in coping with the limitations of the FAA data structures.
Data Formats
The RGL data is compiled in IBM Lotus Notes which is a flat-file database system. Flat-file systems derive their name by being the electronic equivalent to a card file system such as you might find in a recipe box. Each data element is replicated on each record so that reviewing any record (flat file) gives complete information on that entry. The advantage of flat-file systems is that they are easy to understand because the human mind also works natively in this format. The disadvantages are mainly the difficulty of updating or extracting information and the needless replication of much information. For example, if a PMA holder holds 25,000 approvals then 25,000 flat-files are required each of which contains the name and address of the holder. Changing the holder’s address then requires 25,000 changes to the database. In a relational database the name and address is entered only once and is linked to the part information by a reference number. So changing the address in a relational system requires only one database change.
The downloadable version of the PMA database is in Microsoft Access 2003 format which is a relational database. The FAA does not use any of the relational capability of Access, but merely stores information in four separate data tables each reflecting a certain time frame. Many people assume that because this data is contained in a Microsoft Access database it is database data; it is not. The material is raw data, unedited and organized in word processing format. It could just as easily be contained in a spreadsheet or a word processing document. The Access tables do provide some facility where the data can be manipulated, but a certain amount of skill with the Access program is required.
RGL Structure
Most people will interact with the FAA PMA information through the web based RGL database. Perhaps the most useful tool provided is the search window or text box. Enter the term you wish to find and the listings containing the term will be delivered. The only danger here is that the results of the query may yield Too Much Information (TMI). The upper limit of the query return is 1,000 items even when the actual count is 7 or 8,000. In either case the result is nearly useless because it’s still TMI. The tool is best used with a specific part number.
In group format the RGL provides three different “views” of the data:
1. By Make
2. By PMA Holder
3. By Part Number
By Make View
The By Make view refers to the make of the type certificated item upon which the PMA item can be installed. The view is useful when the number of PMA items for a given make is comparatively small such as Air Tractor or Avions Pierre Robin. However, it’s another case of TMI with Boeing, Airbus, McDonnell Douglas or any other make that enjoys a great many approvals. The danger here is that there are a great many makes that are misidentified because of the tradition of associating a type certificated item with a manufacturing company. Consider the venerable Canadian bush aircraft known originally as the de Havilland DHC-2 Beaver. When de Havilland of Canada ceased operations it sold the type certificate to Boeing who then sold it to Bombardier who finally dealt it off to Viking Air where it resides today. So when a PMA manufacturer applies for approval of a DHC-2 part he may identify it as de Havilland or Boeing of Canada or Bombardier or Viking. The FAA apparently doesn’t bother evaluating the draft PMA supplement prepared by the PMA Holder and will likely as not simply approve it as written. So it will end up in the FAA PMA database with the maker name chosen by the PMA holder. The examples of this misidentification error type are legion so it requires a great deal of rather specific and esoteric aviation history to fully exploit the By Make view.
By PMA Holder
This view is, as least superficially, a very valuable viewing tool. It’s drawbacks, like the By Make view, are not readily apparent, and also require a certain depth of aviation knowledge to grasp. To understand the problems and limitations you must first understand how the data is compiled for entry into the database. The entire focus of the RGL PMA data process is to get the data where it can be viewed by the public. There has been little thought or effort applied to accuracy or maintenance. The PMA supplements are read into the database as written regardless of errors or unintended consequences. The By PMA Holder sorting is then done by compilation of the literal name of the PMA holder. For example there are separate entries for “Free Flight Limited Partnership” and for “Free Flight, Limited Partnership” the only difference being the presence of a comma in one of the names. Other companies will be separated because one listing has a five digit zip code and another a nine digit code.
Likewise there are no provisions for updating the information in the database. When a PMA holder moves to a new location its address will change and supplements issued with the new address will be viewed by the RGL as from a different company. This rote entry of data schema also fails to acknowledge corporate mergers and acquisitions. There are at least 500 PMA holder entries in the FAA PMA database for companies that no longer exist because they have been absorbed into another company and the PMA’s reissued under the acquiring company’s name. Usually the part number of the PMA item will not change so the result may be several entries for the same part all under different company names. The casual user will be confused by this and assume the part is being made by several different companies when, in reality, it’s only one part listing made by a single PMA holder under several different names.
So the review of data in the PMA Holder view must be considered only a start of the data acquisition process and not one that yields an accurate, all encompassing view.
By Part Number
Of the three views available, this is the most interesting and probably most productive. The opening view sorts all entries with a PMA part number in ascending order. There is a menu bar at the top of the screen for jumping to the first number or letter in the sort. At first glance you may wonder why this view exists at all. With over 400,000 entries in the database separating them into 36 starting points (26 letters and 10 numbers) would still yield over 11,000 entries at each point; far too many to scroll through and another classic case of TMI. What makes the view useful at all is that each of the displayed fields can be sorted further. At the end of each of the field names are a set of triangles called “Twisties.” Clicking the triangle set will re-sort the data display by that field. Click the twisty once and the listing will be displayed in ascending order. Click it again and the sort order changes to descending.
Most of the data fields do not yield much useful information by this technique since the results can be obtained from the other methods more easily. The Date field, however, is different.
When the view opens the data is sorted to display all entries by part number in ascending order. Click the Date twisty and the data is re-sorted to show the entries in ascending date order. (Blank date enries will be shown first.) Click the twisty again and the data will be displayed in descending date order. This is most useful in seeing what new data has been added to the database. However, as is usually the case, there is a catch. The date used is the date of the PMA supplement and not the date of entry meaning that a supplement dated two years ago, but entered just yesterday will be sorted two years down the list. So the wonderful idea that first appears, that there is a way of seeing what’s new in the database, is an illusion. Because most data is a month or two months old before it’s entered into the RGL it won’t be readily apparent without some scrutiny. Just reviewing the first 10 pages or so of data won’t really tell you everything that’s new. The problem could be easily avoided by dating each entry as it’s added to the database and then providing a view sorted by the entry date. Of course this could result in criticism of the FAA when PMA’s are not entered until 10 years after approval so it isn’t likely a data entry date will be added any time soon.
The Access tables
The FAA previously published its PMA data in Access 97 tables. This data was very flawed primarily because the data was transcribed by hand from supplements into database format. Such labor intensive and mind numbing work is susceptible to errors ranging from simple typos to oversight or outright laziness where transcribers abbreviate or eliminate data entries difficult to transcribe.
The current Access tables are composed mainly of machine transcribed information which is much more accurate. (Some entries with the original errors survive from the old Access 97 tables so the resulting data still contains original errors.) The machine transcription process begins with reading the PMA supplements composed in Microsoft Word into Lotus Notes format through a complex, Word macro that utilizes the Word Object Model programming language capability. The Access tables are then created by exporting the data from Lotus Notes into Access format. The result is a generally highly reliable representation of the data contained in the supplement.
Data errors common to both the RGL and Access tables
(1) Sequential supplement entries: Parts may be approved more than once. For example a part may be originally approved for a Boeing 737 and at some later date also for the 747 and 757. Each new approval will be reflected on an additional supplement which is forwarded to Oklahoma City and dutifully entered into the RGL. This can and does result in multiple entries for the same part with slightly different application information. In extreme cases there may be dozens of entries for the same part; the record is 113.
(2) Mergers and moves: Production approvals are site specific and ordinarily non transferable. That means when a company moves, merges, is acquired or otherwise undergoes a status change, the production approval for the old name or location is invalidated although the design approval is unchanged. The company will resubmit their data for approval under the new name or location and the FAA will ordinarily grant such approval. The usual, but not exclusive, practice is for the MIDO to issue a new PMA letter with all previous parts embraced in supplement 1 to the new PMA letter. Sometimes this practice is followed when a PMA holder's supplements have become confused by multiple revisions. When this paperwork arrives at Oklahoma City the data is entered into the FAA tables resulting in additional duplication. So you will frequently find instances of duplicate parts for the same company the only difference being the date of approval. You will also find duplicate entries for parts manufactured by companies that are absorbed by companies who, in turn, are absorbed by other companies each obtaining new approvals along the way. (Airesearch to Garrett to AlliedSignal to Honeywell, International for example.) There are currently over 500 mergers and company moves where duplications occur. This amounts to more than 30,000 parts listings. An exception is holding companies such as Heico which owns the stock of companies, but not the PMA's themselves.
(3) Type certificate holder merges: The acquisition of McDonnell Douglas by Boeing blurs the line between these two companies. In actuality, McDonnell Douglas has retained its separate corporate identity while becoming a wholly owned subsidiary of Boeing. Some recent PMA approvals have been issued on Boeing Company, Long Beach Division aircraft formerly considered to be of McDonnell Douglas manufacturer while many others retain the old name. Some PMA approvals list the McDonnell Douglas line as manufactured by Boeing which the FAA simply passes through the system without correction. Thus, the RGL will contain the name supplied on the PMA supplement which may be technically incorrect. The only sure method is to check the ownership of the type certificate.
(4) Supplement revisions: From time to time there will be issued revisions to existing supplements. The rules that govern what is or is not or should be in a revision and how it is to be handled vary from MIDO to MIDO. In some cases a revision is precisely that; a later document that replaces a previous document with each entry in the previous issue being echoed in the later issue. In other cases only certain listings that have been revised will appear in the later issue leaving the reader to wonder if the other listings have been dropped or "unapproved." Even within the same MIDO there can and do exist variations in how these matters are handled because the PMA holders draft the supplements and revisions seemingly without much oversight from the FAA inspectors. For example, an original issue may list 14 items and a revision only 8, with 5 being different from the 14 in the original issue. Probably this means that 11 of the original issue are unchanged and 5 new items are added in the revision and 3 are revised, but there isn't much of a guarantee that assumption is correct. Additionally, we've found a total of 38 different schemes for indicating revisions such as 28 Rev, 28 R1, 28 revised, 28 Rev A, 28 reissued, 28 corrected, or ambiguous indicators such as 28 2nd reissue. (Does that mean there was an original reissue, a first reissue and this 2nd reissue is actually the third revision or does it simply mean this is revision 2?) Because of this confusion the RGL and Access tables will contain all the listings for all the revisions which again amounts to TMI when there are 14 revisions to a supplement with 155 listings.
Access Table Field Problems
(1) FullPMAHolder Field: The PMA Holder field contains the name and address of the individual or company to whom the PMA was issued. As explained earlier in this article, companies are sometimes shown in the database under different names. Attempting to extract meaningful information from inconsistent name and address information will have spotty performance. You may have to run several different queries each with different parameters to locate all the parts for a particular manufacturer then you can’t be sure when you’ve got them all.
(2) PartName Field: The part name field is of limited value for finding parts. Remember that the construction parameters for this data are based on raw data with no attempts made to standardize naming. For example, a 12 volt generator may be found under any or all of the following part names: 12 volt generator, Generator, 12 volt, 12 VDC Generator, Generator set, 12-volt, Gen., 12/25 vdc Gen., etc. While it is possible to locate some items by name, the results will be spotty and usually insufficiently specific. For example, searching for “seal” will succeed, but a list of over 7,000 seals isn’t really very helpful. You would best to ignore this field for trying to locate parts and regard it as having some value in describing parts located through other methods. Some listings do not have names as they reflect a group of parts described on a master drawing list (MDL) so the line entry may indicate the MDL or simply be blank.
(3) PartNumber Field: This field is not as limited as the Part_Name field, but suffers from great problems. Sometimes the field will contain a valid PMA part number and sometimes it will have a wordy description that has little relevance to a part number. Actual example: “IAW/MDL NO. 95-FS520-D01, Revision IR, dtd 6/30/95 or Later FAA Approved Revision “ Permeating this field are several thousand incidents of multiple or compound part numbers. A multiple part number is exactly that, more than one part number on the line. A compound number is usually a single number with multiple variations such as P/N 12345-1, -2, -3, -4, -5. The compound numbers may be delimited by commas, as above, or slashes (12345-1 /2 /3 /4 /5), spaces (12345-1 2 3 4 5) or most insidiously of all implication [12345-x or 12345( )]. Usually you can get around these limitations when searching for a single part by text searching just for the base part number without the extension. Access has the ability to search a field for the presence of a certain sequence of text characters. The same technique can be applied to RGL searches.
(4) ApprovedReplace Field: This field suffers from the same limitations as the PartNumber in that it contains multiple and/or compound OEM part numbers. It may also contain the name of the OEM company (sometimes in various formats, e.g P&W, PCE, Pratt & Whitney, PWA, etc.) or omit the name of the actual OEM giving the usually false impression that the OEM part is manufactured by the manufacturer of the type certificated item. Frequently the given OEM name is wrong, not because the data has been transcribed incorrectly, but because the source information itself is incorrect. Even with expert knowledge in the structure of aviation part numbers it may be nearly impossible to determine the actual manufacturer of the OEM part. Airframe and engine manufacturers frequently contract with more than one company to supply an OEM part and the OEM part may be composed of piece parts manufactured by other companies. So, without some kind of special knowledge, the determination of the actual OEM of a particular PMA part is always an exercise in supposition.
(5) ApproveBasis Field: This field is largely descriptive having limited value in locating parts. You can text search this field for a drawing number or some other arcane reference to parts, but mostly the field isn’t much good for finding parts. An exception is when you want to find parts by a specific approval method such as identicality. But even here you need to be careful; we've seen some pretty creative approval means such as "Similarity" and "Identicalness." In addition to the approval basis, this field may hold references to the design data such as a drawing number, an agreement between the PMA producer and OEM, and/or other elements. Sometimes the design data is eliminated entirely for ease of duplication and brevity in the tables. In some entries the approval method is only implied such as when only an STC number is specified thereby implying a Test and Computation method of approval.
(6) Model Field: While sounding simple enough, this field can have some unexpected problems. Since the table subject is PMA parts it would be logical to assume that the field would list the model of the PMA parts. It does not; it’s the make and model of the item upon which the PMA part may be installed. Sounds simple enough after explanation, but
problems arise from the potpourri of manufacturer names in use. In this era of mergers and acquisitions knowing the correct manufacturer name is more often an art than a science. Some examples: You’ll find Beech, Beechcraft, Raytheon, Raytheon/Beech, Beech/Raytheon and other combinations expressing a single manufacturer. Did you know that Aerospace Technologies of Australia (formerly known as Government Factories) is also referred to as Boeing of Australia? How about Learjet and Canadair which are also part of the Bombardier stable. Is it Fairchild or Fairchild/Dornier or is it Daimler Benz Aerospace which owns Dornier? There are also many, many variations of names for the same manufacturer. One source of confusion is Pratt & Whitney and Pratt & Whitney Canada which are separate companies. The key thing to remember when searching for type certificate holder names is to be creative. Often it’s better to search by model rather than manufacturer.
The actual models listed follow the maker’s name and have as many or more permutations as manufacturers. A Sikorsky S-61 can be described as S61, S-61, 61 series, 61M, 61N/M etc. When searching for models, search as text and pare down your search parameter to the most basic item; 61 in the above example. Another problem is the difficulty determining which models belong to which manufacturers. Many PT-6 and PW-1000 series engines are listed as Pratt and Whitney when they should be Pratt & Whitney Canada for example.
(7) SupDate Field: Be especially attentive to supplement dates. Frequently supplements will be revised. Rather than removing the revised supplement from the RGL database the revision is simply added to the database which results in multiple listings for the same set of parts. Sometimes there will be as many as 10 or 15 revisions so you should choose only the one with the latest date as being the correct entry.
(8) SupNumber Field: Supplements are generally sequentially issued, but not always. Sometimes supplements are canceled before or after issuance and sometimes entire supplement series' are replaced by later series'. Thus, this number (or letter or other indicator) must be viewed with caution since knowing the context or history of PMA issuances to a particular holder is needed in order to evaluate the meaning of this field. Even outdated series' are contained the FAA RGL.
General Caveats
(1) Defective Approvals: The current FAA system is governed by 14 CFR § 21.303 which considers that PMA parts may be installed on TC or TSO approved items or upon other PMA items. Frequently these PMA parts are installed on appliances such as magnetos and carburetors that have wide airframe or engine eligibility making them difficult and confusing to classify under the present system. The problem arises when the PMA part is approved for installation on the appliance rather than upon the TC item where the appliance is installed. The number of these defective approvals indicates that perhaps the system should be changed. PMA parts for auxiliary power units (APU's), covered by TSO, also fall into this category making them quite difficult to locate in the data. Usually the airframe manufacturer and model upon which the APU can be installed is set forth in the database. However, there are also many instances where the manufacturer of the APU and the APU model appear instead of the aircraft where the APU may be installed. The lack of consistency results in difficulty in isolating the desired information.
(2) Duplicate entries: There are many thousands of duplications in the FAA data. The duplications are of three broad types:
(a) Multiple submission to Oklahoma City. The FAA RGL system is entirely dependent upon the various Manufacturing Inspection District Offices (MIDO’s) around the country for data supply. The Oklahoma City data compilers do not edit or proof information received from the district offices; they simply enter it. If the information is submitted twice to Oklahoma City it is generally entered twice.
(b) Multiple approvals. A part may be approved more than once and reflected on separate supplements to the PMA letter. Each supplement is processed into the FAA data resulting in what seems to be duplicate entries. Sometimes there are separate approvals that simply don't seem to make sense. Why, for example, would a part be approved one month and then again one month later with the same approval authority and application? Sometimes the supplement will reflect duplicate approvals for the same part and the same applications.
(c) Human error. It is inevitable when many people work on a common task certain elements will be duplicated simply through oversight. For example, a stack of PMA supplements may be processed for entry by one clerk who then goes to lunch. Another clerk may discover the stack of supplements and process them again without the first person’s knowledge. This results in identical entries because the flat-file data system can not provide software safeguards that would preventing duplication.
(3) Missing Entries: If a MIDO fails to supply a supplement then the data compilers are Oklahoma City have no way of knowing it exists and the data will not appear in the database. We know of approximately 40,000 approvals that are not in the FAA data and there are doubtless many thousands more. A cursory examination of data apparently missing from the RGL suggests that possibly 30% of all PMA activity is unreported because the supplements have never been forwarded from the MIDO's to to Oklahoma City.
Summary
The importing thing to keep in mind when working with the FAA data is that it is only a collection of information with no distillation intelligence applied. This means there are no software safeguards to prevent duplications or common errors. Compiling information from multiple sources into a single collection will invariably introduce contradictions in method that results in data inconsistency that may then be regarded as an error. (P&W in one case and Pratt & Whitney in another; both correct denominations, but inconsistent with each other.)
While these comments may be viewed largely as critical of the FAA data, that is not the intent. The FAA makes the data available, but they don't feel compelled to structure it into any particular format other than how it originates. The substance of the data is present in the FAA tables and can be extracted and compiled into worthwhile, meaningful information by a person skilled in database techniques. The FAA RGL may also be wholly adequate for simple inquires or the construction of single-purpose lists.
For intensive investigation of PMA parts and holders, third party software is recommended. Be careful of offerings that simply repackage the FAA data with all its short comings and then offer it at high cost as you won't get much for your money. The economically priced PMA Parts Finder program from Aviation Data Research is recommended. This program overcomes most of the limitations seen in the FAA methods. This makes possible much more detailed and relevant analyses using professional database techniques than is possible working with the raw data. For example, finding all PMA equivalents of a list of 150,000 OEM part numbers in one operation. The PMA Parts Finder also includes all known Canadian PDA, Australian APMA and New Zealand after market approvals, that do not appear in the FAA data.