AD 60-26-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Martin Corporation | 188A | LOCKHEED All Model 188 Aircraft |
| aircraft | Lockheed Martin Corporation | 188C | LOCKHEED All Model 188 Aircraft |
Unsafe Condition
Failure of the clamp or flange of the swirl straightener assembly resulted in overheating the nacelle area causing extensive damage to the nacelle, and failures of the retaining clamp and cracks in the flange area caused by dynamic loads from sugar scoop deflection of exhaust gases.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove the present sugar scoop and lower bellmouth, install a new extended lower bellmouth to mate with the engine, relocate fire sensing elements on the structural shroud, tack-weld vanes to clips on the straightener assembly perimeter, add rubbing strips on the tailpipe shroud door, and drill holes in the nacelle cooling duct assembly as per Lockheed S/B No. 430.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
at the first engine change after December 14, 1960
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Lockheed Martin Corporation 188A and 188C aircraft models
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Swirl Straightener Scoop
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_60-26-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 60-26-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED All Model 188 Aircraft Subject: Swirl Straightener Scoop Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/14/1960 Make: Lockheed Martin Corporation Model: 188A | 188C Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 60-26-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 60-26-04 SUBJECT HEADING: LOCKHEED All Model 188 Aircraft ACTION: SUMMARY: DATES: Effective December 14, 1960. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 60-26-04 LOCKHEED: Amdt. 234 Part 507 Federal Register December 14, 1960. Applies to All 188 Aircraft. Compliance required as indicated. Failure of the clamp or flange of the swirl straightener assembly resulted in at least two cases of overheating the nacelle area causing extensive damage to the nacelle. In addition, there have been a number of failures of the retaining clamp and cracks in the flange area of this assembly caused by dynamic loads imposed by the sugar scoop deflection of exhaust gases. The following modifications shall be accomplished to correct the above conditions at the first engine change after December 14, 1960. (a) Remove the present sugar scoop and the lower bellmouth. Install a new lower bellmouth of extended length to mate properly with the engine after removal of the sugar scoop. When this rework has been accomplished, it will be necessary to relocate the fire sensing elements on the structural shroud. (b) Tack-weld the vanes to the clips located on the perimeter of the straightener assembly. (c) Add rubbing strips on the tailpipe shroud door and drill holes in the nacelle cooling duct assembly to cool the bellmouth. (The above items must be accomplished in accordance with Lockheed S/B No. 430, which covers this same subject.) This directive effective December 14, 1960. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_60-26-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 60-26-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED All Model 188 Aircraft Subject: Swirl Straightener Scoop Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/14/1960 Make: Lockheed Martin Corporation Model: 188A | 188C Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 60-26-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 60-26-04 SUBJECT HEADING: LOCKHEED All Model 188 Aircraft ACTION: SUMMARY: DATES: Effective December 14, 1960. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 60-26-04 LOCKHEED: Amdt. 234 Part 507 Federal Register December 14, 1960. Applies to All 188 Aircraft. Compliance required as indicated. Failure of the clamp or flange of the swirl straightener assembly resulted in at least two cases of overheating the nacelle area causing extensive damage to the nacelle. In addition, there have been a number of failures of the retaining clamp and cracks in the flange area of this assembly caused by dynamic loads imposed by the sugar scoop deflection of exhaust gases. The following modifications shall be accomplished to correct the above conditions at the first engine change after December 14, 1960. (a) Remove the present sugar scoop and the lower bellmouth. Install a new lower bellmouth of extended length to mate properly with the engine after removal of the sugar scoop. When this rework has been accomplished, it will be necessary to relocate the fire sensing elements on the structural shroud. (b) Tack-weld the vanes to the clips located on the perimeter of the straightener assembly. (c) Add rubbing strips on the tailpipe shroud door and drill holes in the nacelle cooling duct assembly to cool the bellmouth. (The above items must be accomplished in accordance with Lockheed S/B No. 430, which covers this same subject.) This directive effective December 14, 1960. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.
Related Airworthiness Directives
2023-10-02
final ruleAirworthiness Directives; Transport and Commuter Category Airplanes
Unsafe Condition: Radio altimeter anomalies that are undetected by the automation or pilot, particularly close to the ground (e.g., landing flare), could lead to loss of continued safe flight and landing. Additional...
2018-11-02
final ruleAirworthiness Directives; Lockheed Martin Corporation/Lockheed Martin Aeronautics Company
Unsafe Condition: Aileron control rod assemblies, which contain the discrepant part, do not provide adequate load carrying capabilities due to the missing 7/8-inch internal threads in the bore of the aileron control...
2015-22-07
final ruleAirworthiness Directives; Lockheed Martin Corporation/Lockheed Martin Aeronautics Company Airplanes
Unsafe Condition: The circumferential fuselage splice at fuselage-station (FS) 695 is subject to widespread fatigue damage (WFD), which could lead to loss of residual strength and rapid decompression of the cabin.
2015-20-01 Recurring
final ruleAirworthiness Directives; Lockheed Martin Corporation/Lockheed Martin Aeronautics Company Airplanes
Unsafe Condition: The left and right lower surface panels of the wings are subject to widespread fatigue damage (WFD), which could result in reduced structural integrity of the airplane.