# STC SE01537AT

- Type: Supplemental type certificate
- Status: Current, Reissued
- Holder: Whelen Aerospace Technologies, United States
- Description: Replace counterweights on Lycoming O-540-A1A5, -A1B5, -A1C5, -A1D5, and IO-540-C1B5 engines.
- Applied: May 3, 1996
- Status date: July 22, 2022
- Product: Engine
- Certification basis: Part 21
- Data sheets: [TCDS 1E4](https://openairdocs.org/tcds/1E4), [TCDS E-295](https://openairdocs.org/tcds/E-295)
- Certificate PDF: https://openairdocs.org/files/sha256/8d/37/8d37b4f7aec7ad471c5fe3eb24043b2e25eac5ffc26839c5d29640a2affc0137
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A20BFA2E85A54DFF862588C3005DAF97.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SE01537AT

## ADs that name it (0)

None.

## Approved models (5)

- Textron Lycoming AVCO Corporation IO-540-C1B5 ([TCDS 1E4](https://openairdocs.org/tcds/1E4))
- Textron Lycoming AVCO Corporation O-540-A1A5 ([TCDS E-295](https://openairdocs.org/tcds/E-295))
- Textron Lycoming AVCO Corporation O-540-A1B5 ([TCDS E-295](https://openairdocs.org/tcds/E-295))
- Textron Lycoming AVCO Corporation O-540-A1C5 ([TCDS E-295](https://openairdocs.org/tcds/E-295))
- Textron Lycoming AVCO Corporation O-540-A1D5 ([TCDS E-295](https://openairdocs.org/tcds/E-295))

## What the certificate says

Read from the PDF's text layer, without the form's printed wording; the layout is lost and the order can differ. The PDF is the record.

Title: (for) Christina M. UnderwoodManager, Atlanta ACO Branch Compliance and Airworthiness Division Aircraft Certification Service SE01537AT Whelen Aerospace Technologies 51 Winthrop Road Chester, CT 06412 13 Civil Air Regulations E-295 Lycoming IO-540-C1B5, O-540-A1A5, A1B5, A1C5, A1D5 Replace counterweights on the O-540-A1A5, A1B5, A1C5, A1D5 and IO-540-C1B5 engines as documented to LoPresti Speed Merchants "Comanche Model PA-24-250 Propeller Conversion Installation Instructions," report No. 007, Rev IR, dated August 12, 1997 or later FAA Approved revisions.

The installer must determine whether this design change is compatible with previously approved modifications. The midification is limited to installations on Piper model PA24-250 aircraft with Lycoming engines as stated in the type design change statement. If the holder agrees to permit a person to use this certificate to alter a product, the holder must give this person written evidence of that permission.

May 3, 1996 January 16, 2019; July 22, 2022 December 30, 1997 2

SE01537AT 2

## Every issue (2)

- July 22, 2022: Reissued, Current. [certificate](https://openairdocs.org/files/sha256/8d/37/8d37b4f7aec7ad471c5fe3eb24043b2e25eac5ffc26839c5d29640a2affc0137)
- January 16, 2019: Reissued, Historical. [certificate](https://openairdocs.org/files/sha256/b4/26/b426922e157c5bae612f3eedeae9940daabc0b440d42e291753a7ad9526a0a5b)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.