STC COMPATIBILITY VERIFICATION

New STC Compatibility Verification Services Offered


Terry Bowden, FAA Consultant DER  is collaborating with Certified Aeronautical Products and other FAA designees across multiple technical disciplines to offer a new service called STC Compatibility Verification.  The service is aimed at providing installers the means to address the compatibility verification with reliable and professional results.

In a recent letter to the FAA, the National Transportation Safety Board (NTSB) made recommendations aimed at improving safety of aircraft, which have multiple modifications.  The letter cites several actual crashes that were attributed to conflicting modifications made on aircraft via Supplemental Type Certificate (STC) installations.  One of those aircraft had 22 STC modifications since leaving the factory.

See the NTSB Letter Here.

The FAA has responded by issuing a SPECIAL AIRWORTHINESS INFORMATION BULLETIN # CE-12-37.  This document, titled "STC Modification Airworthiness Interrelationship Effects" focuses on Airspeed Limitations and Markings.

See the FAA SAIB CE-12-37 Here.

With the number and complexity of STC modifications ever increasing on individual aircraft, safety could be compromised by adding a modification that itself might be considered a safety improvement.  The check for STC compatibility for some airplanes has become quite difficult for installers to manage. Installers may lack the expertise for making the compatibility check.  Some situations may demand qualifications that only experienced Designated Engineering Representatives (DERs) or Designated Airworthiness Representatives (DAR's) can provide. 

What drives this?

STC installers are required to address the following standard statement under the STC "Limitations and Conditions".

This approval should not be extended to other aircraft of this model on which other previously approved modification[sic] are incorporated, unless it is determined by the installer that the interrelationship between this change and any other previously approved modifications will produce no [sic] adverse effect upon the airworthiness of that airplane.

STC installers have long been subject to this (or similar) STC limitations.  Are you one of the STC installers that have struggled with knowing how to make this determination?

Why not let qualified professionals handle this?

Contact Terry today

(254) 715-4773

barnstmr@aol.com

What does the STC Compatibility Verification entail?
We run a background check on the aircraft through a study of FAA records or other information you provide regarding the aircraft's history of major repairs and alterations.  We compare the scope of previous changes vs. the proposed changes and review them against FAA airworthiness requirements.  We provide you, the installer, with a thorough assessment of the proposed STC to be installed and it's potential impact on or affects from previously installed modifications.  We will make recommendations as necessary to address incompatibilities that should be resolved to ensure safe implementation of the proposed STC.

How much does this cost?

Costs can vary depending on the number of prior mods and the complexities of the systems or airworthiness considerations involved.  We charge a flat fee of  $500.00 to address most circumstances.  This includes comparing up to 4 STCs and up to 8 hours of work.  If the job entails more time, we charge an hourly rate that can depend on the resources needed.  (This rate is generally around $100.00 per hour.) 

It is worth having the peace of mind that the job was done right!

Contact Terry today

(254) 715-4773

barnstmr@aol.com

Additional FAA Authority - Vintage DER

Terry is pleased to announce that his DER delegation has recently been expanded to cover the following additional FAA approval authority.... as a Vintage DER (V-DER).

Although Terry has developed his career around FAA certification on more modern aircraft, he has a special affinity toward older airplanes. In some ways it is a payback for the unique opportunities Terry had as a kid to restore and fly several old airplane types with his dad. With this added authority, Terry looks forward to assisting vintage airplane owners to "Keep the Antiques Flying"!

View the "Vintage" tab at the top of this page for more information about this special FAA delegation authority.

NOT ALL 337's ARE FIELD APPROVALS

As a DER, I am frequently quizzed on this often misunderstood process.

Not everybody understands the difference between a "field approval" vs. "337 with DER Approved Data". So.... here is an effort to explain.

A&P/IA's are trained that they must use FAA approved data when executing the FAA form 337 to document major repairs and alterations for the aircraft's return-to-service. For many years, it was customary to go to an FAA FSDO safety inspector for "field approval" of data when it was not readily available. This can still be done. However, the overall decline of experienced FSDO inspectors has resulted in fewer and fewer field approvals being done. These days, DER's can bridge this gap.

The "field approval" term refers to the case of obtaining data approval from the FSDO safety inspector. Alternatively, an equivalent means of approving an alteration is through "DER support of a 337", which means the data approval is from a DER. Either way, you end up with FAA approved data.

Field Approvals can be one way to obtain FAA Approved data, but DER's can also provide FAA approved data. A common misunderstanding of the process is the erroneous belief that all 337's are "field approvals". Not true. In reality, a "field approval" is not needed when using DER(s) - as long as a DER approves all of the applicable regulations associated with the alteration or repair.

i.e. DER approved data = FAA approved data

With a drawing and DER approval in hand, any IA can execute a 337 and reference the drawing in block 8 of the 337 as the "approved data". Once completed, the IA will forward the 337 paperwork directly to the FAA to be filed in OKC. There is no need to call a FSDO inspector, except in certain circumstances. Ask your IA abut this. It is routine.



The following is an excerpt from FAA AC 23-21, Change 1...
One of the methods of obtaining approved data for a particular alteration is to utilize a DER to provide necessary approved data. This methodology is described in FAA Order 8110.45, “Use of Data Approved by Designated Engineering Representatives to Support Major Alteration,” dated 8/30/02, and Order 8110.37C, “Designated Engineering Representative (DER) Guidance Handbook,” dated 9/30/98. Both Orders can be found at the FAA website http://www.faa.gov. When you identify a requirement for data during an alteration, you may contact a DER with the authority, as listed in Order 8110.37C, to generate the report and submit approved data. The use of a DER to develop FAA approved data can save time because it is an efficient means to ensure completeness of the required data. [If 100 percent of the necessary data is DER approved data, no further FAA approval is required.—Change 1] When contacting a DER, only DERs specifically authorized by their managing ACO are permitted to approve data for major repairs and alterations.
__________________