When aircraft equipment isn't STCed
You've just returned from AOPA Expo where you've spotted a piece of equipment that you are sure will complete your airplane. So you run to your mechanic and tell him what you've found. Then he says, "Yeah, those look great and I think they would improve your airplane, but they're not STCed for installation in your airplane. We could try to get a field approval." You're left scratching your head — what's a field approval, and why does the prospect of applying for one seem to cause grief for your normally happy-go-lucky mechanic?
A field approval is a design approval for a major alteration (major repairs also can be field approved but most owners aren't involved in determining repairs) that is approved by a flight standards district office (FSDO) aviation safety inspector (ASI). Field approvals are for major alterations that do not require detailed engineering analysis.
"The field approval process is designed to utilize the expertise of the person doing the change," said one FAA employee.
This definition answers the question of why some mechanics aren't comfortable with field approvals — they may not have much expertise in the area your modification addresses. GA mechanics tend to have developed their skills in three areas. They either love to work on engines, airframes, or the electrical part of the airplane. Many mechanics are comfortable in two of the three, but few are competent in all three areas.
Nonstandard standards
"We're called flight standards, but we're anything but standardized," said a senior FAA aviation safety inspector (ASI). This truth is based on the fact that the decision to approve a major alteration by the field approval process is a subjective decision by each ASI, although this approval decision may be swayed by FSDO policies that vary from office to office. Some ASIs are comfortable signing off field approvals, and some aren't. The honest ones will tell you that they're confident about their ability to judge the effects of certain types of alterations, but don't have enough experience to sign off other types without engineering help. Other ASIs seem to think they're engineers and appear to sign off anything — and a few send every application on for engineering approval. That's the way it's always been. Will a recent rewrite of the guidelines for the field approval process result in a more uniform system? Some owners and mechanics hope so, while others are very happy with the old state of field approvals.
Supplemental type certificates (STCs)
Commonly installed modifications such as bigger engines, speed slope windshields, auxiliary fuel tanks, strobe-light systems, and wheel and brake upgrades are almost always preapproved (by the FAA) for installation through the supplemental type certificate (STC) process. The installation instructions included with an STC are approved data.
STCed installations are easy since they're completely packaged — order the modification kit, upon arrival open the box and inventory the parts, study the installation instructions, install the parts, test the installation, insert the flight manual supplements that apply to the installation into the pilot's operating handbook (POH), fill out a major repair and alteration form (commonly called a 337) detailing the change, send a copy to the local FSDO, and make an entry in the maintenance records.
If we consider an STCed modification to be like a prix fixe meal at a good restaurant — point to the entrée you want and soon the complete meal is delivered — then a field approval can be considered to be the same meal without the restaurant, wait staff, chef, and dishwasher. This is not a true representation of the process because many maintenance shops are very field-approval savvy.
An initial application for a field approval requires planning and time since the applicant (usually the mechanic acting on behalf of the owner) must coordinate with his ASI to ensure that the desired alteration can be approved. New guidelines that are in the process of being finalized mention the need for what seems to be piles of paperwork (the FAA calls it a standard data package, or SDP) detailing (by illustration and text) how the modification will be accomplished and how the pertinent regulations will be complied with, as well as data such as the location and weight of the alteration.
An SDP often requires a flight manual supplement (FMS) and an instructions for continued airworthiness (ICA) document. After the SDP is submitted to the ASI, he approves the modification based on whether the SDP fulfills all the requirements and whether the requested modification is safe to approve without engineering approval.
If the ASI decides that the SDP is incomplete, he sends it back for revision. Usually the applicant has failed to adequately address one of the items listed in the application checklist. If the ASI decides the modification needs engineering approval, he sends it up to the local FAA aircraft certification office (ACO), where the FAA engineers work.
After the ACO checks the data, it can be approved or sent back to the applicant. Work can begin only after the application has been approved.
If the ASI says the installation needs engineering approval, the applicant has the option of contracting with an FAA- designated engineering representative (DER) to supply approved data for a field approval. If the data passes engineering scrutiny, the DER sends the applicant an FAA Form 8110-3, which is approved data. Since ACOs are often understaffed, many applicants opt to pay a DER for a quick turnaround on the engineering approval.
Occasionally a mechanic will inform an owner that there is equipment on his airplane that isn't approved. Perhaps a previous installer thought it was a minor alteration, or the paperwork was lost. One way to return the airplane to airworthy status is through a field approval. After-the-fact field approvals almost always require a visual inspection by the ASI and, because of the time involved, are a headache for everyone.
Having run through all the requirements of applying for a field approval, often the process is quick and easy. Again, it depends on the relationship between the maintenance shop and the ASI. I've gotten many field approvals signed off by phoning my ASI, telling him what I wanted, and mailing the application and the data that supported the installation. A signed approval returned in a couple of weeks.
Approved and acceptable data
I installed a new instrument panel that moved the pilot's flight instruments into a more modern "sacred six" configuration in my 1966 Cessna 182J. I bought a precut instrument panel from a friend (who owned a metal machining business) who had previously completed an identical panel change. I asked for a copy of the 337 that showed that his panel was approved by field approval. I used his previously field-approved 337 form as acceptable data for my field approval application. If there is one key to obtaining a field approval, it's a copy of a field-approved 337 for the installation of the modification you want on your make and model of airplane.
Owners can identify a major alteration that has been field approved by looking in block 3 of the 337 form. A field-approved modification will have a sentence that reads: "The technical data identified herein has been found to comply with applicable airworthiness requirements and is hereby approved for use only on the above-described aircraft, subject to conformity inspection by a person in paragraph 43.7." This is followed by the ASI's signature.
Every experienced airframe and powerplant (A&P) mechanic has a file folder packed with copies of approved field approvals. That file, along with a good working relationship with the local ASI, is the key for obtaining field approvals.
Regional differences
The field approval system has been in place for more than 40 years, but there are differences among the FAA regions (there are nine covering the United States) as to how major alterations should be field approved. An item that is commonly approved in one region may be modification non grata in a neighboring region.
A major alteration is defined as an alteration not listed in the aircraft, aircraft engine, propeller, or appliance specifications (type certificate data sheets, or TCDS) that might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness.
The Alaska region, by virtue of the importance of light aircraft in that state, has produced a handbook that shines a lot of light on the field approval process. This manual, now in its fourth revision, is available online ( www.alaska.faa.gov/flt_std/aws/alterat.htm#start).
Alaska defines appreciably as capable of being perceived or measured. This definition is not universal.
The inconsistencies in interpretation of field approval guidelines between individual ASIs and different regions have been a headache for FAA administrators, and more than once during past FAA Administrator Jane Garvey's tenure she was called to task at public forums over these inconsistencies. In response to the grumbling from the field, the FAA recently drafted new guidelines for field approvals.
In July 2001, AOPA's Government and Technical Affairs office attended an FAA field-approval public meeting and encouraged the FAA to streamline the field approval process so new safety-enhancing technologies could be more easily installed in GA aircraft.
In October 2002, the new guidelines were incorporated into the Airworthiness Inspector's Handbook (Order 8300.10).
Change 15, which replaced change 10, contained expanded guidelines on field approvals for ASIs. When this change arrived at the regional offices of the FAA, an uproar quickly arose that echoed through the halls of FAA headquarters in Washington, D.C. It seemed that no one was happy with the changes. Mechanics in the field claimed that the field approval process had stopped. The most common topic discussed in A&P mechanic inspection authorization (IA) renewal meetings (held all over the country in February and March) was field approvals. The gremlin was in paragraph 9 of change 15, titled "Alterations not eligible for field approval."
Change 15
FAA regulations are a work in progress — they are constantly evolving in an effort to clarify issues that are found to hinder or obscure the intent of the order. The impetus for these changes comes from aircraft owners and operators, FSDOs, ASIs, and aircraft certification offices (ACOs).
Paragraph 9 was written to straighten out the inconsistencies that existed across the country regarding which alterations the ASIs could sign off on by field approval, and which could only be approved after engineering studies by the ACO. This paragraph also lists (in order number 8110.46) the alterations that require an STC or an amendment to the type certificate for approval. It's not hard to see why this section was confusing — most alterations on the list of modifications that required an STC for approval were followed by an asterisk. The asterisk noted that the item could be approved by a means other than an STC. Paragraph 9 seemed to be contradictory — it narrowed the list, and then gave almost every case an exemption. The order confused everyone.
Some ASIs, who had been approving field approvals for decades, seemed to take the new order as an insult, and reacted. They stopped signing any field approvals, and kicked every application up the ladder to the local ACO. The ACOs became swamped with requests for field-approval engineering studies. The ACOs called Washington, asking for clarification and increased staffing.
New rules
Reacting to the uproar from its members, AOPA quickly asked the FAA to rescind this order since the "attempt to improve and standardize field approval service nationwide had the opposite effect, most noticeably in Alaska." Visit the Web site ( www.aopa.org/whatsnew/regulatory/reg_field_approval.html) for an explanation of AOPA's role in this issue.
In Alaska, the uproar was so vigorous that the FAA temporarily rescinded change 15 less than two months after it took effect. AOPA petitioned the FAA to rescind change 15 in the rest of the country as well. The FAA denied that request, the result being that there are now two sets of field approval rules in force.
In hindsight, change 15 was grossly misunderstood — all it did was state the regulatory basis for field approvals and mandate that all field approval applications had to be accepted, even if the ASI involved did not have personal expertise with the type of project applied for.
As this article goes to press, change 16 has been drafted and the notorious section 9 has been reduced to two paragraphs and a table. An advisory circular (AC) titled "Standardizing procedures for requesting field approval of data, major alterations, and repairs" is in the draft stage. This AC (32 pages in draft) will augment the 1987 (AC 43.9-1) version titled "Instructions for completion of Form 337, major repair or alteration, airframe, powerplant, propeller or appliance."
A few Alaska maintenance shops depended on the field approval process to upgrade airplanes they sold. Before change 15 arrived, these companies had no problem getting field approvals because of the trust that had built up between the ASIs and the company owners. With the introduction of change 15, those relationships changed.
"I've been doing some of these modifications under the field approval process for 30 years, and now my PMI (principal maintenance inspector) says I have to get approved data from a DER to do what I've been doing for 30 years," complained the owner of one Alaska maintenance and rebuild shop. One of the most experienced Alaska modification manufacturers told me that it's impossible to get an STC in Alaska because the ACO is severely understaffed. With no provision to get their modifications approved by STC, many Alaska shops lived and died by their ability to get field approvals.
AOPA felt the impact from change 15 when it tried to replace the old-style brakes on the sweepstakes Waco with a more modern set of Cleveland wheels and brakes. This change, like many others that used to get a routine sign-off for a safety-related field approval application, became a big deal after change 15 was introduced. There are cases where the field approval process has been abused — major modifications to flight control systems that by their nature required an engineering study were sometimes approved via the field approval process. One of the goals of the new rules was to define more closely the parameters of modifications that require STC approval.
It's too early to tell whether change 16 and the new advisory circular will smooth out the process of obtaining field approvals. Perhaps all the fuss will die down in time. As an Alaska mechanic told me, "Every time we get a new ASI it takes us two or three years to train them. Then things go pretty well, until we get another one." It looks as if the new field approval rules may have the same effect.
E-mail the author at [email protected].
A Little Guidance
Owners who are willing to get on the Internet and search for STCs that apply to their desired alteration may find that it's usually easier, and almost always quicker, to buy an applicable STC than it is to spend the time developing a full package of field approval data. View an up-to-date page on STCs online ( www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/MainFrame?OpenFrameSet).
Further guidance regarding field approvals is available on the FAA Web site ( www.faa.gov/aircraft/air_cert/design_approvals/field_approvals/).
If there's no STC, then the next step is to find out if the equipment you intend to install has received FAA PMA approval. PMA stands for parts manufacturing approval — it means the FAA has inspected the manufacturing process and it complies with agency guidelines. If there are two or more manufacturers of your desired equipment, the road to obtaining a field approval will be smoother if you specify the FAA PMA-approved equipment.
Be sure to ask the seller of the equipment if he can supply a copy of a field-approved 337 form for your make and model of airplane.
Next ask your mechanic if he is willing to help you get a field approval for the desired modification. He may not be — if he isn't, ask around until you find one who is.
The regulations say that owners can travel to other regions and work with any ASI on field approvals. Type-specific owner groups ( www.aopa.org/members/clubs/) often can assist owners by supplying acceptable data in the form of previously approved 337s, and providing information on the whereabouts of field approval-savvy ASIs. — SWE
