91-21-01 R1
FR doc 96-14220 · 61 FR 29003AD 91-21-01 R1Published 1996-06-07Effective 1996-06-27
Requires the upgrade of the engine exhaust system to a new design configuration; and also establishes inspection intervals for engines incorporating the new design configuration, for engines incorporating the design configuration…
1 correction to this AD FAA · 1996-09-06
Correction published 1996-09-06
- Issued by
- Federal Aviation Administration
- Published
- 1996-09-06
- Document
- Federal Register 96-22773 · Final rule; correction
- Corrects
- the version published June 7, 1996 at 61 FR 29003
This document makes a correction to Airworthiness Directive (AD) 91-21-01 R1 applicable to Textron Lycoming Model TIO-540-S1AD reciprocating engines that was published in the Federal Register on June 7, 1996 (61 FR 29003). The reference to the New York Aircraft Certification Office in Note 3 following the paragraph describing the procedure for obtaining an alternative method of compliance was omitted. This document corrects that omission. In all other respects, the original document remains the same.
A correction restates part of an AD that was published incorrectly. It is not an additional requirement and it does not change the AD number or its effective date.
Source: Federal Register document 96-22773, retrieved 2026-08-15
Full official abstract
This amendment revises an existing airworthiness directive (AD), applicable to Textron Lycoming Model TIO-540-S1AD reciprocating engines, that currently requires the upgrade of the engine exhaust system to a new design configuration; and also establishes inspection intervals for engines incorporating the new design configuration, for engines incorporating the design configuration required by a previous AD, and for engines not yet incorporating either design configuration. This amendment clarifies that an exhaust system disassembly is not necessary when inspecting the exhaust system after the installation of the new design One-piece Exhaust Riser Kit, and Manifold Retaining Kit. This amendment is prompted by reports from operators requesting clarification of two paragraphs in the compliance section. The actions specified by this AD are intended to prevent cracking or distortion of engine exhaust system flanges, V-band coupling, and pipes, which could result in engine compartment fire and smoke entering the cabin with possible loss to the aircraft.