AD 77-19-02
final rule
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Learjet Inc. | 23 | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24 | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24A | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24B | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24B-A | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24C | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24D | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24D-A | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24E | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24F | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 24F-A | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25 | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25A | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25B | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25C | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25D | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
| aircraft | Learjet Inc. | 25F | Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes |
Unsafe Condition
Cracked, bent, broken, or worn bolt (part 5) in the cabin door locking mechanism could allow unwanted door openings if the pilot disregards the door warning system.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect and replace bolt/pin (part 5) per SB 23/24/25-280; inspect door locking mechanism for wear/defects including hole diameter measurement; submit reports on defective bolts/pins to FAA.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required as per Table I: Initial inspections based on airplane total time in service, with intervals of 3,000 hours' time in service thereafter. Door locking mechanism inspections must be done if bolt defects are found, or at specified hour milestones.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Gates Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, and 25F with 36-inch wide cabin doors, all serial numbers.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Cabin Door Locking Mechanism
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_77-19-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-19-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 2...Show more Subject: Cabin Door Locking Mechanism Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/20/1978 Make: Learjet Inc. Model: 23 | 24 | 24A | 24B | 24B-A | 24C | 24D | 24D-A | 24E | 24F | 24F-A | 25 | 25A | 25B | 25C | 25D | 25F 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: 77-19-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3265 AD NUMBER: 77-19-02 SUBJECT HEADING: Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes ACTION: SUMMARY: DATES: Effective July 20, 1978. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-19-02 GATES LEARJET: Amendment 39-3040 as amended by Amendment 39- 3265. Applies to all serial numbers of Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes certificated in all categories having a 36- inch wide (as opposed to a 24-inch wide) cabin door. COMPLIANCE: Required as indicated in accordance with Compliance Table I set forth in this AD, unless already accomplished. To assure proper locking of the cabin upper door when the inside handle is in the locked position and to prevent possible unwanted door openings that may occur if a pilot disregards the door warning system accomplish the following at the time intervals noted in Table I of this AD: TABLE I COMPLIANCE TIMES I N S P E C T I O N T I M E S Airplane Total Time In Service (Hours) Paragraph "A" Bolt Inspection & Replacement Paragraph "B" Locking Mechanism Inspection Initial Inspection/ Replacement Interval for Repetitive Inspections/ Replacement Initial Inspection Interval for Repetitive Inspections 0 - 2,999 Prior to or upon the accumulation of 3,075 hours' time in service Each 3,000 hours' time in service thereafter In accordance with asterisk (*) paragraph below or upon accumulation of 6,075 hours' time in service, whichever occurs first In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection 3,000 - 5,999 Within 75 hours' time in service after the effective date of this AD Each 3,000 hours' time in service thereafter In accordance with asterisk (*) paragraph below or upon accumulation of 6,075 hours' time in service, whichever occurs first In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection 6,000 - up Within 75 hours' time in service after the effective date of this AD Each 3,000 hours' time in service thereafter Within 75 hours' time in service after the effective date of this AD In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection * The door locking mechanism inspection must be accomplished any time the bolt inspection required by Paragraph "A" of this AD reveals a cracked, bent, broken or worn bolt. A. Inspect and replace, at the time intervals noted in Table I above, the bolt or pin identified as (5) in Figure I of this AD in accordance with Gates Learjet Service Bulletin SB 23/24/25-280 dated July 15, 1977 or later approved revisions and as summarized below: 1. Remove the bolt, or if applicable, pin from the upper door rod control assembly and visually inspect it for cracks, breaks, bends, or wear. If any of the aforementioned defects are found accomplish the door locking mechanism inspection required by Paragraph "B" of this AD prior to the next flight; and 2. Replace the bolt or pin removed in Paragraph A.1. of this AD with a new Gates Learjet part number 2311490-8 bolt, or a new AN3-21 bolt modified in accordance with the above noted Service Bulletin, and secure using an AN960D10 Washer and either a new MS20365-1032 Nut or AN310-3 Nut and MS24665-132 Cotter Pin. B. Inspect, at the time intervals noted in Table I above, the cabin door locking mechanism in accordance with Gates Learjet Service Bulletin SB 23/24/25-280 dated July 15, 1977 or later approved revisions, and as summarized below: 1. Drill out rivets and remove cabin upper door inner panel. 2. Remove and inspect door locking mechanism for wear and defects in accordance with Learjet Service Manual Inspection Requirements. The maximum allowable diameter (measured in any direction) of the hole in which the (5) bolt is installed is .201 inches. Replace any excessively worn or defective parts prior to the next flight. 3. Reinstall door locking mechanism and using rivets, reinstall the inner panel. 4. Check door locking mechanism for free movement with no binding thru entire operating travel. Correct any binding prior to the next flight. 5. Energize door warning system and check its operation for proper functioning. C. Submit a written report on any cracked, broken, bent or worn (5) (See Figure I of this AD) bolts or pins discovered during inspections required by this AD to the FAA via a letter to FAA, Chief, Engineering and Manufacturing Branch (ACE-210), 601 E. 12th Street, Kansas City, Missouri 64106 or an FAA M or D report (FAA Form 8330-2). The report must include airplane model, serial number, airplane total time-in-service, bolt or pin total time-in-service and statements describing the condition of the bolt and the hole including dimensions of the hole determined in accordance with Paragraph B.2. of this AD. (Reporting approved by the Office of Management and Budget under OMB No. 04-R0174.) D. The actions made mandatory by Paragraphs A, B, and C of this AD are no longer required when Gates Learjet Door Modification Kit AMK 78-2 is installed. E. Airplanes may be flown in accordance with FAR 21.197 to a base where this AD can be accomplished. F. Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. Amendment 39-3040 became effective on September 26, 1977. This amendment 39-3265 becomes effective July 20, 1978. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_77-19-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-19-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 2...Show more Subject: Cabin Door Locking Mechanism Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/20/1978 Make: Learjet Inc. Model: 23 | 24 | 24A | 24B | 24B-A | 24C | 24D | 24D-A | 24E | 24F | 24F-A | 25 | 25A | 25B | 25C | 25D | 25F 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: 77-19-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3265 AD NUMBER: 77-19-02 SUBJECT HEADING: Airworthiness Directives; Gates Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F Airplanes ACTION: SUMMARY: DATES: Effective July 20, 1978. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-19-02 GATES LEARJET: Amendment 39-3040 as amended by Amendment 39- 3265. Applies to all serial numbers of Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes certificated in all categories having a 36- inch wide (as opposed to a 24-inch wide) cabin door. COMPLIANCE: Required as indicated in accordance with Compliance Table I set forth in this AD, unless already accomplished. To assure proper locking of the cabin upper door when the inside handle is in the locked position and to prevent possible unwanted door openings that may occur if a pilot disregards the door warning system accomplish the following at the time intervals noted in Table I of this AD: TABLE I COMPLIANCE TIMES I N S P E C T I O N T I M E S Airplane Total Time In Service (Hours) Paragraph "A" Bolt Inspection & Replacement Paragraph "B" Locking Mechanism Inspection Initial Inspection/ Replacement Interval for Repetitive Inspections/ Replacement Initial Inspection Interval for Repetitive Inspections 0 - 2,999 Prior to or upon the accumulation of 3,075 hours' time in service Each 3,000 hours' time in service thereafter In accordance with asterisk (*) paragraph below or upon accumulation of 6,075 hours' time in service, whichever occurs first In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection 3,000 - 5,999 Within 75 hours' time in service after the effective date of this AD Each 3,000 hours' time in service thereafter In accordance with asterisk (*) paragraph below or upon accumulation of 6,075 hours' time in service, whichever occurs first In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection 6,000 - up Within 75 hours' time in service after the effective date of this AD Each 3,000 hours' time in service thereafter Within 75 hours' time in service after the effective date of this AD In accordance with asterisk (*) paragraph below or upon accumulation of each 6,000 hours' time in service after initial inspection * The door locking mechanism inspection must be accomplished any time the bolt inspection required by Paragraph "A" of this AD reveals a cracked, bent, broken or worn bolt. A. Inspect and replace, at the time intervals noted in Table I above, the bolt or pin identified as (5) in Figure I of this AD in accordance with Gates Learjet Service Bulletin SB 23/24/25-280 dated July 15, 1977 or later approved revisions and as summarized below: 1. Remove the bolt, or if applicable, pin from the upper door rod control assembly and visually inspect it for cracks, breaks, bends, or wear. If any of the aforementioned defects are found accomplish the door locking mechanism inspection required by Paragraph "B" of this AD prior to the next flight; and 2. Replace the bolt or pin removed in Paragraph A.1. of this AD with a new Gates Learjet part number 2311490-8 bolt, or a new AN3-21 bolt modified in accordance with the above noted Service Bulletin, and secure using an AN960D10 Washer and either a new MS20365-1032 Nut or AN310-3 Nut and MS24665-132 Cotter Pin. B. Inspect, at the time intervals noted in Table I above, the cabin door locking mechanism in accordance with Gates Learjet Service Bulletin SB 23/24/25-280 dated July 15, 1977 or later approved revisions, and as summarized below: 1. Drill out rivets and remove cabin upper door inner panel. 2. Remove and inspect door locking mechanism for wear and defects in accordance with Learjet Service Manual Inspection Requirements. The maximum allowable diameter (measured in any direction) of the hole in which the (5) bolt is installed is .201 inches. Replace any excessively worn or defective parts prior to the next flight. 3. Reinstall door locking mechanism and using rivets, reinstall the inner panel. 4. Check door locking mechanism for free movement with no binding thru entire operating travel. Correct any binding prior to the next flight. 5. Energize door warning system and check its operation for proper functioning. C. Submit a written report on any cracked, broken, bent or worn (5) (See Figure I of this AD) bolts or pins discovered during inspections required by this AD to the FAA via a letter to FAA, Chief, Engineering and Manufacturing Branch (ACE-210), 601 E. 12th Street, Kansas City, Missouri 64106 or an FAA M or D report (FAA Form 8330-2). The report must include airplane model, serial number, airplane total time-in-service, bolt or pin total time-in-service and statements describing the condition of the bolt and the hole including dimensions of the hole determined in accordance with Paragraph B.2. of this AD. (Reporting approved by the Office of Management and Budget under OMB No. 04-R0174.) D. The actions made mandatory by Paragraphs A, B, and C of this AD are no longer required when Gates Learjet Door Modification Kit AMK 78-2 is installed. E. Airplanes may be flown in accordance with FAR 21.197 to a base where this AD can be accomplished. F. Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. Amendment 39-3040 became effective on September 26, 1977. This amendment 39-3265 becomes effective July 20, 1978. 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.