AD 59-21-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Martin Corporation | 188A | LOCKHEED Model 188 Series Aircraft |
| aircraft | Lockheed Martin Corporation | 188C | LOCKHEED Model 188 Series Aircraft |
Unsafe Condition
Repeated loosening of wing leading edge attachment screws between the fuselage and the outboard nacelles.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually inspect the leading edge attachment screws every 50 hours of service time and tighten any loose screws. Retighten all screws every 300-hour interval to 25 to 40 inch-pounds torque. Replace NAS 517-3 screws with LPHT 517-3 screws and torque to 45-55 inch-pounds if removed.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required as indicated.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Lockheed Model 188 Series Aircraft (188A, 188C)
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Wing Leading Edge Screws
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_59-21-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 59-21-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED Model 188 Series Aircraft Subject: Wing Leading Edge Screws Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 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Lockheed Martin Corporation Model: 188A | 188C Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 59-21-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 59-21-02 SUBJECT HEADING: LOCKHEED Model 188 Series Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 59-21-02 LOCKHEED: Applies to All Model 188 Series Aircraft. Compliance required as indicated. Due to repeated loosening of wing leading edge attachment screws between the fuselage and the outboard nacelles, the following inspections shall be conducted: (a) At each 50 hours of service time, visually inspect the leading edge attachment screws, top and bottom, from the fuselage to the outboard nacelles, paying particular attention to screws adjacent to nacelles. Tighten any screws found loose. (b) At 300-hour intervals retighten all affected screws to 25 to 40 inch-pounds torque. The above inspection program may be discontinued upon the removal of the NAS 517-3 screws from all leading edge attachments, top and bottom, and the installation of LPHT 517-3 screws. Torque all new leading edge attaching screws to 45-55 inch-pounds. (Lockheed Service Bulletin 88/SB-334 covers this same subject.) NOTE: LPHT-517 refers to Lockheed Specification for a Long-Lok, Polyvinyl insert, High torque screw. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_59-21-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 59-21-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED Model 188 Series Aircraft Subject: Wing Leading Edge Screws Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 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: 59-21-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 59-21-02 SUBJECT HEADING: LOCKHEED Model 188 Series Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 59-21-02 LOCKHEED: Applies to All Model 188 Series Aircraft. Compliance required as indicated. Due to repeated loosening of wing leading edge attachment screws between the fuselage and the outboard nacelles, the following inspections shall be conducted: (a) At each 50 hours of service time, visually inspect the leading edge attachment screws, top and bottom, from the fuselage to the outboard nacelles, paying particular attention to screws adjacent to nacelles. Tighten any screws found loose. (b) At 300-hour intervals retighten all affected screws to 25 to 40 inch-pounds torque. The above inspection program may be discontinued upon the removal of the NAS 517-3 screws from all leading edge attachments, top and bottom, and the installation of LPHT 517-3 screws. Torque all new leading edge attaching screws to 45-55 inch-pounds. (Lockheed Service Bulletin 88/SB-334 covers this same subject.) NOTE: LPHT-517 refers to Lockheed Specification for a Long-Lok, Polyvinyl insert, High torque screw. 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.