AD 79-16-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C28 | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C28B | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C28C | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30 | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30G | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30G/2 | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30M | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30P | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30R (T703-AD-700) | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30R/1 (T703-AD-700B) | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30R/3 | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30S | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30U | DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines |
Unsafe Condition
Accessory drive gearbox failure due to the use of generator idler gearshaft P/N 6898980, 6898591, or 77 tooth spur idler gearshaft P/N 6898652, which could result in engine power loss.
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Required Actions
Remove the referenced gearshafts from service prior to reaching 9000 cycles for 250-C28 series engines or 2000 cycles for 250-C30 engines. For gearshafts within 50 cycles of the limit on the effective date, comply within 100 cycles.
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Compliance Time
Prior to reaching the specified cycle limits (9000 cycles for 250-C28, 2000 cycles for 250-C30). For gearshafts within 50 cycles of the limit on the effective date, compliance required within 100 cycles.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Rolls-Royce Corporation Model 250-C28 (including variants) and 250-C30 (including variants) series engines equipped with generator idler gearshaft P/N 6898980, 6898591, or 77 tooth spur idler gearshaft P/N 6898652 installed in Bell 206L-1 and Sikorsky S-76 rotorcraft.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Accessory Drive Gearbox
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_79-16-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 79-16-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines Subject: Accessory Drive Gearbox Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 01/11/1980 Make: Rolls-Royce Corporation Model: 250-C28 | 250-C28B | 250-C28C | 250-C30 | 250-C30G | 250-C30G/2 | 250-C30M | 250-C30P | 250-C30R (T7...Show more 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: 79-16-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3650 AD NUMBER: 79-16-06 SUBJECT HEADING: DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines ACTION: SUMMARY: DATES: Effective January 11, 1980. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 79-16-06 DETROIT DIESEL ALLISON: Amendment 39-3527 is further amended by Amendment 39- 3650. Applies to all Model 250-C28 and 250-C30 series engines equipped with generator idler gearshaft P/N 6898980, or 6898591, or 77 tooth spur idler gearshaft P/N 6898652 installed in, but not limited to Bell 206L-1 and Sikorsky S-76 rotorcraft certificated in all categories. Compliance required as indicated unless previously accomplished. To preclude engine power loss as a result of an accessory drive gearbox failure, remove the referenced gearshafts from service prior to reaching 9000 cycles if installed in a 250-C28 series engine and prior to reaching 2000 cycles if installed in a 250-C30 engine. For those gearshafts that are within 50 cycles of the appropriate limit on the effective date of this AD, compliance is required within 100 cycles. For the purpose of this AD, a cycle is defined as an attempted or completed start, or a motoring of the engine using the starter. The start counter is activated and accumulates the count of cycles only when the ignition circuit is energized. Therefore, cycles due to motoring with the starter (ignition circuit not energized) must be added to the cycle count. (Detroit Diesel Allison Commercial Engine Bulletins CEB 72-2003 for the 250-C28B and CEB 72-3003 for the 250-C30 also pertain to this subject.) Amendment 39-3527 became effective August 15, 1979. This amendment 39-3650 becomes effective January 11, 1980. FOOTER:
Document Text
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AD Final Rules - DRS_79-16-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 79-16-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines Subject: Accessory Drive Gearbox Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 01/11/1980 Make: Rolls-Royce Corporation Model: 250-C28 | 250-C28B | 250-C28C | 250-C30 | 250-C30G | 250-C30G/2 | 250-C30M | 250-C30P | 250-C30R (T7...Show more 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: 79-16-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3650 AD NUMBER: 79-16-06 SUBJECT HEADING: DETROIT DIESEL ALLISON Model 250-C28 and 250-C30 Series Engines ACTION: SUMMARY: DATES: Effective January 11, 1980. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 79-16-06 DETROIT DIESEL ALLISON: Amendment 39-3527 is further amended by Amendment 39- 3650. Applies to all Model 250-C28 and 250-C30 series engines equipped with generator idler gearshaft P/N 6898980, or 6898591, or 77 tooth spur idler gearshaft P/N 6898652 installed in, but not limited to Bell 206L-1 and Sikorsky S-76 rotorcraft certificated in all categories. Compliance required as indicated unless previously accomplished. To preclude engine power loss as a result of an accessory drive gearbox failure, remove the referenced gearshafts from service prior to reaching 9000 cycles if installed in a 250-C28 series engine and prior to reaching 2000 cycles if installed in a 250-C30 engine. For those gearshafts that are within 50 cycles of the appropriate limit on the effective date of this AD, compliance is required within 100 cycles. For the purpose of this AD, a cycle is defined as an attempted or completed start, or a motoring of the engine using the starter. The start counter is activated and accumulates the count of cycles only when the ignition circuit is energized. Therefore, cycles due to motoring with the starter (ignition circuit not energized) must be added to the cycle count. (Detroit Diesel Allison Commercial Engine Bulletins CEB 72-2003 for the 250-C28B and CEB 72-3003 for the 250-C30 also pertain to this subject.) Amendment 39-3527 became effective August 15, 1979. This amendment 39-3650 becomes effective January 11, 1980. FOOTER:
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Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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