# Proposed AD 98-NM-137-AD: Short Brothers Model SD3-30, SD3-60, SD3 SHERPA, and SD3-60 SHERPA Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-21-22
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 23, 1999, 64 FR 33439
- Comments due: July 23, 1999
- Became: [AD 99-21-22](https://openairdocs.org/ad/99-21-22)
- Docket: 98-NM-137-AD
- FR document: 99-15930
- Official PDF: https://openairdocs.org/files/sha256/2c/21/2c2111b8e72fb22849d99310d56c2be86eb45f8c1a2bdcc07dcf3e15d78e0b84 (from https://www.govinfo.gov/content/pkg/FR-1999-06-23/pdf/99-15930.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/06/23/99-15930/airworthiness-directives-short-brothers-model-sd3-30-sd3-60-sd3-sherpa-and-sd3-60-sherpa-series
- Page: https://openairdocs.org/proposed/98-NM-137-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-30, SD3-60, SD3 SHERPA, and SD3-60 SHERPA series airplanes. This proposal would require a one-time borescope inspection to detect corrosion of the shear decks and ribs of the left and right stub wings, follow-on corrective actions, if necessary; and drilling of new drain holes in the lower shear decks. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent corrosion of the stub wing shear decks and ribs, which could result in cracking or failure of the stub wing structure.

## Notices in this docket

- Jun 23, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-15930, comments due Jul 23, 1999 (https://www.federalregister.gov/documents/1999/06/23/99-15930/airworthiness-directives-short-brothers-model-sd3-30-sd3-60-sd3-sherpa-and-sd3-60-sherpa-series)

---
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.