AD 93-25-05

final rule

ALLISON Model 250-C20S Engines

AD Number
93-25-05
Status
final_rule
Effective Date
Product Category
engine
Docket
91-ANE-50
FR Citation
This information is not available.
Technical illustration of an aircraft turbine engine assembly
Problem area Engine

Applicability

TypeManufacturerModelDetails
engine Rolls-Royce Corporation 250-C20S ALLISON Model 250-C20S Engines

Unsafe Condition

Bolt fretting and fatigue failure of the main engine driveshaft flex coupling bolts, bushings, and nuts could lead to driveshaft detachment and engine failure.

AI-generated summary from the source AD text. Verify against the official source before acting.

Required Actions

Within 90 days after the effective date, inspect the main engine driveshaft and replace the driveshaft flex coupling bolts, bushings, and nuts per Soloy Corporation Service Bulletin No. 04-780. Replace driveshafts with elongated bolt holes with serviceable parts.

AI-generated summary from the source AD text. Verify against the official source before acting.

Compliance Time

Within 90 days after the effective date of this AD

AI-generated summary from the source AD text. Verify against the official source before acting.

Affected Aircraft

Allison Model 250-C20S engines modified by Soloy Conversion, Ltd. STC SE2352NM, installed on but not limited to Cessna 206 and 207 airplanes.

AI-generated summary from the source AD text. Verify against the official source before acting.

Federal Register Abstract

Driveshaft Flex Coupling Bolts, Bushings, and Nuts

Applicability Source Text

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AD Number:
93-25-05
Document Type:
AD Final Rules
Docket Number:
91-ANE-50
Subject Heading:
ALLISON Model 250-C20S Engines
Subject:
Driveshaft Flex Coupling Bolts, Bushings, and Nuts
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
02/22/1994
Make:
Rolls-Royce Corporation
Model:
250-C20S
Product Type:
Engine
Product Subtype:
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 93-25-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   91-ANE-50

AMENDMENT:   39-8771

AD NUMBER:   93-25-05

SUBJECT HEADING:   ALLISON Model 250-C20S Engines

ACTION:  

SUMMARY:  

DATES:   Effective February 22, 1994.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:   93-25-05 ALLISON: Amendment 39-8771. Docket 91-ANE-50.
Applicability: Allison Model 250-C20S turbine engines, as modified by Soloy Conversion, Ltd., Supplemental Type Certificate (STC) SE2352NM, installed on but not limited to Cessna 206 and 207 airplanes.
Compliance: Required as indicated, unless accomplished previously.
To prevent bolt fretting and fatigue failure, main engine driveshaft detachment, and engine failure, accomplish the following:
(a) Within 90 days after the effective date of this AD, inspect the main engine driveshaft and replace the driveshaft flex coupling bolts, bushings, and nuts in accordance with Soloy Corporation Service Bulletin No. 04- 780, dated December 11, 1991. Replace with a serviceable part those main engine driveshafts with elongated bolt holes.
(b) 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 Manager, Seattle Aircraft Certification Office. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Seattle Aircraft Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Seattle Aircraft Certification Office.
(c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.
(d) The inspection, and replacement, if necessary, shall be done in accordance with the following service bulletin:

Document No.	Pages	Revision	Date
Soloy Corporation
Service Bulletin
No. 04-780	1-3	Original	December 11, 1991
Total Pages: 3.			

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 Soloy Corporation, 450 Pat Kennedy Way, S.W., Olympia, WA 98501- 7298; telephone (206) 754-7000. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on February 22, 1994.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_93-25-05.html
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Details
AD Number:
93-25-05
Document Type:
AD Final Rules
Docket Number:
91-ANE-50
Subject Heading:
ALLISON Model 250-C20S Engines
Subject:
Driveshaft Flex Coupling Bolts, Bushings, and Nuts
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
02/22/1994
Make:
Rolls-Royce Corporation
Model:
250-C20S
Product Type:
Engine
Product Subtype:
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 93-25-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   91-ANE-50

AMENDMENT:   39-8771

AD NUMBER:   93-25-05

SUBJECT HEADING:   ALLISON Model 250-C20S Engines

ACTION:  

SUMMARY:  

DATES:   Effective February 22, 1994.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:   93-25-05 ALLISON: Amendment 39-8771. Docket 91-ANE-50.
Applicability: Allison Model 250-C20S turbine engines, as modified by Soloy Conversion, Ltd., Supplemental Type Certificate (STC) SE2352NM, installed on but not limited to Cessna 206 and 207 airplanes.
Compliance: Required as indicated, unless accomplished previously.
To prevent bolt fretting and fatigue failure, main engine driveshaft detachment, and engine failure, accomplish the following:
(a) Within 90 days after the effective date of this AD, inspect the main engine driveshaft and replace the driveshaft flex coupling bolts, bushings, and nuts in accordance with Soloy Corporation Service Bulletin No. 04- 780, dated December 11, 1991. Replace with a serviceable part those main engine driveshafts with elongated bolt holes.
(b) 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 Manager, Seattle Aircraft Certification Office. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Seattle Aircraft Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Seattle Aircraft Certification Office.
(c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.
(d) The inspection, and replacement, if necessary, shall be done in accordance with the following service bulletin:

Document No.	Pages	Revision	Date
Soloy Corporation
Service Bulletin
No. 04-780	1-3	Original	December 11, 1991
Total Pages: 3.			

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 Soloy Corporation, 450 Pat Kennedy Way, S.W., Olympia, WA 98501- 7298; telephone (206) 754-7000. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on February 22, 1994.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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