Document
IA TB 26-02 October 8, 2025 Page 1 of 2
Interagency Aviation
TECH BULLETIN
IA TB 26-02 October 8, 2025 Page 1 of 2 Subject: Suspected Unapproved Parts (SUPs) Distribution: All Users Background: Suspected Unapproved Parts (SUPs) are parts that are not manufactured under the Production Certificate for a Type Certificated (TC) aircraft or parts for a Supplemental Type Certificate (STC). Per FAR 21.9, all parts installed on aircraft must be approved parts, including appropriate documentation that results in traceability back to an approved parts manufacturing authority. Any part that is not approved is considered a SUP, making it unairworthy and not eligible for installation.
Due to the similarities between UH-1 series parts and Bell 205/212 series parts, the Bell medium series is highly susceptible to installation of SUPs. The issue of SUPs is not new. Nearly 40-50 years ago, SUPs posed a significant problem for Bell helicopter models, as people were purchasing foreign military parts and aircraft and installing those parts on Type Certificated helicopters (Bell 204/205/212). These illegal installations resulted in several accidents during that time, usually caused by the part failing due to it not being made to the same specification as the civilian part. The issue of Suspected Unapproved Parts was addressed in Operational Safety Notice GEN 85-11, along with numerous Safety Notices from Bell.
Discussion: Within the past 12 months, several SUPs have been installed on aircraft contracted by the USFS, rendering those aircraft unairworthy. Recent occurrences reveal that the Certificate of Conformity (the legal term for approved parts) has been altered to read as “Certificate of Conformance” (see Figure 1). Additionally, the parts documentation contains visible spellings and formatting errors. The alterations to the parts documentation was a tactic used in the 1980s as a method for the SUP seller to avoid litigation from operators.
The seller would claim that they did not know that the parts sold were being used on certificated aircraft.
Figure 1: Image from a recent SUP discovered on a USFS contracted aircraft.
The term “Certificate of Conformance” within the fine print indicates a SUP.
In working with Bell to research several of the identified SUPs, Bell confirmed that they IA TB 26-02 October 8, 2025 Page 2 of 2 make the parts, but not under their Production Certificate. Furthermore, the SUPs were manufactured over 30 years ago and sold to either foreign militaries or North Atlantic Treaty Organization (NATO).
To address this issue, Bell has many publications in all their manuals prohibiting the use of military parts on civil aircraft.
While this issue was initially identified in the Bell 205/212 series, it is relevant to all types of aircraft model series, including modern aircraft. The recent increase in SUP discoveries is concerning, as the use of unapproved parts has historically led to numerous accidents— a past neither the Forest Service nor the operators wish to repeat.
Recommendations: • All vendors should provide training to maintenance personnel on how to identify and report SUPs as part of their quality assurance processes for home/base facilities and field operations (field mechanics).
• All parts documentation must be sent to both the FS and OAS Maintenance Inspectors when requesting that an aircraft be Returned to Contract Availability (RTCA). In most cases there will be both FS and DOI inspectors assigned to vendors/aircraft. If there are any questions or concerns regarding parts documentation, please contact an FS/OAS Maintenance Inspector.
• Subscribe to and review SUPs alerts at https://www.faa.gov/aircraft/safety/programs/sups .
• Review applicable Advisory Circulars, including: o AC 21-29 “Detecting and Reporting Suspected Unapproved Parts.” o AC 20-62 “Eligibility, Quality, and Identification of Approved Aeronautical Replacement Parts”.
• Consider attending the FAA’s Safety Team’s ( https://www.faasafety.gov/default.aspx ) free SUPs courses including: o ALC-1366 “What You Need to Know About Aviation Parts” o ALC-1402 “Repair Station Virtual Safety Day-Suspected Unapproved Parts”.
o A third paid course is presented through MyFAA.com ALC-767 “Suspected Unapproved Parts and Counterfeit Parts”.
/s/ Walker Craig /s/ Russel Knight Walker Craig Russel Knight Chief, Division of Technical Services DOI Airworthiness Branch Chief Office of Aviation Services USDA Forest Service