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94-02-01: Impeller

FAA order 94-02-01 is an airworthiness directive in force since February 4, 1994. The FAA's subject line: Impeller. It names the Honeywell T5508D engine: about 3 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: engine.

What it applies to as the FAA lists it

Kind of product: Engine
Makes: Honeywell International Inc.
Models: T5508D
Engine series: Honeywell T5508D 3 aircraft

Dates and paperwork

In force since: February 4, 1994
Docket: 93-ANE-56
Status: Current
The FAA's document: Read the order on the FAA's site

The FAA's summary their words, unchanged

This amendment adopts a new airworthiness directive (AD) that is applicable to Textron Lycoming Model T5508D turboshaft engines. This action requires a cyclic life reduction for the T5508D impeller, a more conservative method for determining low cycle fatigue (LCF) damage to the impeller, and a method for prorating past impeller usage, based on the new LCF counting factors. This amendment is prompted by a report of a rotorcraft accident found to have been caused by an uncontained impeller failure. A subsequent field campaign inspection of high-time impellers utilized by heavy lift operators confirmed 12 more impellers with similar distress. The actions specified in this AD are intended to prevent an impeller failure, which can result in an uncontained engine failure, inflight shutdown, or possible rotorcraft damage.

The order itself the regulatory text, as published

Show the full text (2,864 characters)

94-02-01  Textron Lycoming:  Amendment 39-8798.  Docket 93-ANE-56. 
	Applicability:  Textron Lycoming Model T5508D turboshaft engines, installed on but not limited to Bell 214B helicopters. 
	Compliance:  Required as indicated, unless accomplished previously. 
	To prevent an impeller failure, which can result in an uncontained engine failure, inflight shutdown, or possible rotorcraft damage, accomplish the following: 
	(a)	Within 7 days after the effective date of this AD, conduct a revised impeller operating cycle count (prorate), in accordance with paragraph E of Textron Lycoming Service Bulletin (SB) No. T5508D-0002, Revision 7, dated June 25, 1993. 
	(b)	Following the implementation of the revised cycle count methodology, specified in paragraph (a) of this AD, replace those impellers installed in aircraft that exceed the new life limit, on the effective date of this AD, in accordance with the drawdown requirements defined in Table 1 of Textron Lycoming SB T5508D-0040, dated June 25, 1993. 
	(c)	For those impellers not installed in aircraft on the effective date of this AD, with 8,000 or more cycles in service (CIS), replace with a new or serviceable impeller prior to further flight. 
	(d)	Thereafter, Textron Lycoming Model T5508D impeller, part numbers 2-100-180-13 and 2-100-180-19, are life limited to 8,000 CIS, as defined in Table 1 of Textron Lycoming SB No. T5508D-0002, Revision 7, dated June 25, 1993. 
	(e)	An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Engine Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Engine Certification Office. NOTE:  Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office. 
	(f)	The operationalcyclic counting and replacement of impellers shall be done in accordance with the following service bulletins: 


Document No.
Pages
Revision
Date
 Textron Lycoming
 SB No. T5508D-0002
1-12
7
June 25, 1993 
Total pages:  12. 



Textron Lycoming SB No. T5508D-0040
1-2
Original	
June 25, 1993 
Total pages:  2. 




This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.  Copies may be obtained from Textron Lycoming, 550 Main Street, Stratford, CT 06497.  Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, Attention:  Rules Docket No. 93-ANE-56, 12 New England Executive Park, Burlington, Massachusetts; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 
	(g)	This amendment becomes effective on February 4, 1994.

Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of October 7, 2026. Connections as data: /graph/directive/94-02-01.json · aircraft systems.