AD 60-26-05

final rule

LOCKHEED All Model 188 Series Aircraft

AD Number
60-26-05
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Unknown
FR Citation
This information is not available.
Technical illustration of an aircraft flight control surface and actuator
Problem area Flight controls

Applicability

TypeManufacturerModelDetails
aircraft Lockheed Martin Corporation 188A LOCKHEED All Model 188 Series Aircraft
aircraft Lockheed Martin Corporation 188C LOCKHEED All Model 188 Series Aircraft

Unsafe Condition

Excessive free play in elevator counterweight linkage and potential rupture of elevator booster control valve viscous damper diaphragm could lead to elevator or control column oscillations, compromising flight control effectiveness.

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

Required Actions

Inspect elevator counterweight installation for free play exceeding 1/8-inch and reduce to 1/16-inch or less by replacing bolts/parts. Inspect viscous damper diaphragm for rupture and replace if found. Install spring-loaded cartridge (P/N 840404-1), replace damper with orifice type (P/N 492508-3), rework elevator booster assembly with orifice valve assembly (P/N 804551-1), and modify piston rod end with retaining washers (P/N 839756-1) per Service Bulletins 88/SB-498 and 524.

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

Compliance Time

Within the next 1,000 hours' time in service.

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

Affected Aircraft

Lockheed Model 188A and 188C aircraft, all serial numbers, as covered by AD 60-26-05.

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

Federal Register Abstract

Elevator and Boost Control Valve

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_60-26-05.html
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AD Number:
60-26-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
LOCKHEED All Model 188 Series Aircraft
Subject:
Elevator and Boost Control Valve
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
12/22/1960
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Superseded AD: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Superseded By: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: 60-26-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   60-26-05

SUBJECT HEADING:   LOCKHEED All Model 188 Series Aircraft

ACTION:  

SUMMARY:  

DATES:   Effective December 22, 1960.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
60-26-05 LOCKHEED: Amdt. 236 Part 507 Federal Register December 22, 1960. Applies to All 188 Series Aircraft.

Compliance required as indicated.

(a) Within the next 150 hours' time in service commencing on November 22, 1960, unless already accomplished within the last 300 hours' time in service, inspect the elevator counterweight installation, Lockheed Drawing No. 829912, at airplane center line for evidence of free play as follows: with elevator blocked at extreme down position apply up and down force to balance weight Lockheed P/N 827020-1, and measure total movement of balance weight due to cumulative free play in joints of balance arm linkage. If movement of balance weight due to cumulative free play in system exceeds 1/8-inch inspect each joint in balance arm linkage and reduce the free play by bolt and/or part replacement at one or more of these joints so as to reduce total free play movement of the balance weight to 1/16-inch or less prior to further flight. This inspection must be repeated every 450 hours' time in service. When provisions of paragraph (c)(1) are accomplished, this special inspection may be discontinued.

(b) Within the next 300 hours' time in service, unless already accomplished within the last 700 hours' time in service, and following any occurrence of inflight elevator or control column oscillations, inspect the elevator booster control valve viscous damper diaphragm, Lockheed P/N 813612-1 for evidence of rupture. See Lockheed Electra (Model 188) Overhaul Manual Section 27-1-10 Page 1 for information on evidence of rupture. If such evidence is found the airplane shall not be returned to service until the diaphragm is replaced with a new part, or compliance with paragraph (c)(2) has been accomplished. This inspection must be repeated at periods not to exceed 1,000 hours' time in service until the provisions of paragraph (c)(2) have been accomplished.

(c) The following must be accomplished within the next 1,000 hours' time in service.

(1) Install a spring-loaded cartridge, Lockheed P/N 840404-1, in the elevator counterweight linkage in the manner described by Lockheed Service Bulletin 88/SB-524.

(2) Replace the elevator boost control valve viscous damper, Lockheed P/N 813608-3, with an orifice type damper, Lockheed P/N 492508-3, in accordance with Lockheed Service Bulletin No. 88/SB-524.

(3) Rework the elevator booster assembly in accordance with Lockheed Service Bulletin No. 88/SB-524 to incorporate an orifice valve assembly, Lockheed P/N 804551-1, and modify the booster piston rod end installation to incorporate two retaining washers, Lockheed P/N 839756-1, in accordance with Lockheed Service Bulletin No. 88/SB-498.

(FAA approved Lockheed Service Bulletins 88/SB-498 and 88/SB-524, Lockheed Electra operating information letter No. 13 dated November 1, 1960, Lockheed Alert Bulletin No. 524 dated December 1, 1960, cover portions of this subject.)

This supersedes AD 60-24-02.

This directive effective December 22, 1960.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_60-26-05.html
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 Feedback
Details
AD Number:
60-26-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
LOCKHEED All Model 188 Series Aircraft
Subject:
Elevator and Boost Control Valve
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
12/22/1960
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: 60-26-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   60-26-05

SUBJECT HEADING:   LOCKHEED All Model 188 Series Aircraft

ACTION:  

SUMMARY:  

DATES:   Effective December 22, 1960.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
60-26-05 LOCKHEED: Amdt. 236 Part 507 Federal Register December 22, 1960. Applies to All 188 Series Aircraft.

Compliance required as indicated.

(a) Within the next 150 hours' time in service commencing on November 22, 1960, unless already accomplished within the last 300 hours' time in service, inspect the elevator counterweight installation, Lockheed Drawing No. 829912, at airplane center line for evidence of free play as follows: with elevator blocked at extreme down position apply up and down force to balance weight Lockheed P/N 827020-1, and measure total movement of balance weight due to cumulative free play in joints of balance arm linkage. If movement of balance weight due to cumulative free play in system exceeds 1/8-inch inspect each joint in balance arm linkage and reduce the free play by bolt and/or part replacement at one or more of these joints so as to reduce total free play movement of the balance weight to 1/16-inch or less prior to further flight. This inspection must be repeated every 450 hours' time in service. When provisions of paragraph (c)(1) are accomplished, this special inspection may be discontinued.

(b) Within the next 300 hours' time in service, unless already accomplished within the last 700 hours' time in service, and following any occurrence of inflight elevator or control column oscillations, inspect the elevator booster control valve viscous damper diaphragm, Lockheed P/N 813612-1 for evidence of rupture. See Lockheed Electra (Model 188) Overhaul Manual Section 27-1-10 Page 1 for information on evidence of rupture. If such evidence is found the airplane shall not be returned to service until the diaphragm is replaced with a new part, or compliance with paragraph (c)(2) has been accomplished. This inspection must be repeated at periods not to exceed 1,000 hours' time in service until the provisions of paragraph (c)(2) have been accomplished.

(c) The following must be accomplished within the next 1,000 hours' time in service.

(1) Install a spring-loaded cartridge, Lockheed P/N 840404-1, in the elevator counterweight linkage in the manner described by Lockheed Service Bulletin 88/SB-524.

(2) Replace the elevator boost control valve viscous damper, Lockheed P/N 813608-3, with an orifice type damper, Lockheed P/N 492508-3, in accordance with Lockheed Service Bulletin No. 88/SB-524.

(3) Rework the elevator booster assembly in accordance with Lockheed Service Bulletin No. 88/SB-524 to incorporate an orifice valve assembly, Lockheed P/N 804551-1, and modify the booster piston rod end installation to incorporate two retaining washers, Lockheed P/N 839756-1, in accordance with Lockheed Service Bulletin No. 88/SB-498.

(FAA approved Lockheed Service Bulletins 88/SB-498 and 88/SB-524, Lockheed Electra operating information letter No. 13 dated November 1, 1960, Lockheed Alert Bulletin No. 524 dated December 1, 1960, cover portions of this subject.)

This supersedes AD 60-24-02.

This directive effective December 22, 1960.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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