AD 78-16-03

final rule

Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes

AD Number
78-16-03
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Unknown
FR Citation
This information is not available.

Applicability

TypeManufacturerModelDetails
aircraft Learjet Inc. 23 Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24 Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24B Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24B-A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24C Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24D Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24D-A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24E Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24F Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 24F-A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25 Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25B Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25C Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25D Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 25F Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 35 Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 35A (C-21A) Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 36 Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes
aircraft Learjet Inc. 36A Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes

Unsafe Condition

Failure of the refrigeration condenser fan with part number 6608059-3, which has blades not tapered in thickness from the hub to the tip.

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

Required Actions

Before the next flight, inspect the refrigeration condenser fan part number. If part number 6608059-3 is installed, fabricate and install a placard restricting refrigeration system operation. Replace the fan with part numbers 6608059-1, -2, or -4 to remove the placard and return to normal service.

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

Compliance Time

Before the next flight

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

Affected Aircraft

Learjet Models 23 (SN 23-003+), 24/24A (SN 24-100-24-180), 24B/24B-A (SN 24-181-24-229), 24C/24D/24D-A (SN 24-218, 24-230-24-328), 24E/24F/24F-A (SN 24-329-24-356), 25/25A (SN 25-002-25-066), 25B/25C (SN 25-061, 25-067-25-201, 25-204-25-205), 25D/25F (SN 25-206-25-253), 35 (SN 35-001-35-066), 35A (SN 35-067-35-194), 36 (SN 36-001-36-017), and 36A (SN 36-018-36-040).

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

Federal Register Abstract

Refrigeration Condenser Fan

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_78-16-03.html
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AD Number:
78-16-03
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A,...Show more
Subject:
Refrigeration Condenser Fan
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
08/17/1978
Make:
Learjet Inc.
Model:
23 | 24 | 24A | 24B | 24B-A | 24C | 24D | 24D-A | 24E | 24F | 24F-A | 25 | 25A | 25B | 25C | 25D | 2...Show more
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: 78-16-03
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-3278

AD NUMBER:   78-16-03

SUBJECT HEADING:   Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes

ACTION:  

SUMMARY:  

DATES:   Effective August 17, 1978.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
78-16-03 LEARJET: Amendment 39-3278. Applies to Learjet Model 23 (Serial Numbers 23-003 and up); Model 24 and 24A (Serial Numbers 24-100 through 24-180); Model 24B and 24B-A (Serial Numbers 24-181 through 24-229); Model 24C, 24D and 24D-A (Serial Numbers 24-218, and 24-230 through 24-328); Model 24E, 24F and 24F-A (Serial Numbers 24- 329 through 24-356); Model 25 and 25A (Serial Numbers 25-002 through 25-066); Model 25B and 25C (Serial Numbers 25-061, 25-067 through 25-201, 25-204 and 25-205); Model 25D and 25F (Serial Numbers 25-206 through 25-253); Model 35 (Serial Numbers 35-001 through 35- 066); Model 35A (Serial Numbers 35-067 through 35-194); Model 36 (Serial Numbers 36-001 through 36-017); and Model 36A (Serial Numbers 36-018 through 36-040) airplanes.

COMPLIANCE: Required as indicated unless already accomplished.

To preclude a failure of the refrigeration condenser fan:

A) Before the next flight, remove or lower the tailcone access door, disconnect the aircraft batteries, and inspect the refrigeration condenser fan part number that is rubber stamped on the blade. If the refrigeration condenser fan installed has a part number other than 6608059-3, no further action is required. (The blades on P/N 6608059-3 fans are not tapered in thickness from the hub to the tip.)

B) If Part Number 6608059-3 refrigeration condenser fan is installed, before the next flight fabricate a placard which reads "DO NOT OPERATE REFRIGERATION SYSTEM UNDER ANY CIRCUMSTANCES ON THE GROUND OR IN THE AIR." Install this placard as near as possible to the refrigeration system control switch and operate the airplane in accordance with this restriction.

C) When the Part Number 6608059-3 fan is replaced with either a P/N 6608059-1, 6608059-2 or a P/N 6608059-4 fan, the above required placard may be removed and the airplane returned to normal service. (The blades on the -1, -2 and -4 fans are tapered in thickness from the hub to the tip.)

D) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

NOTE: Gates Learjet Service Bulletins SB23/24/25-284, dated 7/13/78, and SB35/36- 21-3, dated 7/12/78, or later approved revisions, provide inspection and fan replacement procedures, physical characteristics of the fans, and replacement part credit information.

This amendment becomes effective August 17, 1978, to all persons except those to whom it has already been made effective by air mail letter from the FAA dated July 21, 1978.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_78-16-03.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
78-16-03
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A,...Show more
Subject:
Refrigeration Condenser Fan
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
08/17/1978
Make:
Learjet Inc.
Model:
23 | 24 | 24A | 24B | 24B-A | 24C | 24D | 24D-A | 24E | 24F | 24F-A | 25 | 25A | 25B | 25C | 25D | 2...Show more
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: 78-16-03
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-3278

AD NUMBER:   78-16-03

SUBJECT HEADING:   Airworthiness Directives; Learjet Models 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, 25F 35, 35A, 36, and 36A Airplanes

ACTION:  

SUMMARY:  

DATES:   Effective August 17, 1978.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
78-16-03 LEARJET: Amendment 39-3278. Applies to Learjet Model 23 (Serial Numbers 23-003 and up); Model 24 and 24A (Serial Numbers 24-100 through 24-180); Model 24B and 24B-A (Serial Numbers 24-181 through 24-229); Model 24C, 24D and 24D-A (Serial Numbers 24-218, and 24-230 through 24-328); Model 24E, 24F and 24F-A (Serial Numbers 24- 329 through 24-356); Model 25 and 25A (Serial Numbers 25-002 through 25-066); Model 25B and 25C (Serial Numbers 25-061, 25-067 through 25-201, 25-204 and 25-205); Model 25D and 25F (Serial Numbers 25-206 through 25-253); Model 35 (Serial Numbers 35-001 through 35- 066); Model 35A (Serial Numbers 35-067 through 35-194); Model 36 (Serial Numbers 36-001 through 36-017); and Model 36A (Serial Numbers 36-018 through 36-040) airplanes.

COMPLIANCE: Required as indicated unless already accomplished.

To preclude a failure of the refrigeration condenser fan:

A) Before the next flight, remove or lower the tailcone access door, disconnect the aircraft batteries, and inspect the refrigeration condenser fan part number that is rubber stamped on the blade. If the refrigeration condenser fan installed has a part number other than 6608059-3, no further action is required. (The blades on P/N 6608059-3 fans are not tapered in thickness from the hub to the tip.)

B) If Part Number 6608059-3 refrigeration condenser fan is installed, before the next flight fabricate a placard which reads "DO NOT OPERATE REFRIGERATION SYSTEM UNDER ANY CIRCUMSTANCES ON THE GROUND OR IN THE AIR." Install this placard as near as possible to the refrigeration system control switch and operate the airplane in accordance with this restriction.

C) When the Part Number 6608059-3 fan is replaced with either a P/N 6608059-1, 6608059-2 or a P/N 6608059-4 fan, the above required placard may be removed and the airplane returned to normal service. (The blades on the -1, -2 and -4 fans are tapered in thickness from the hub to the tip.)

D) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

NOTE: Gates Learjet Service Bulletins SB23/24/25-284, dated 7/13/78, and SB35/36- 21-3, dated 7/12/78, or later approved revisions, provide inspection and fan replacement procedures, physical characteristics of the fans, and replacement part credit information.

This amendment becomes effective August 17, 1978, to all persons except those to whom it has already been made effective by air mail letter from the FAA dated July 21, 1978.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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