AD 68-25-04

final rule

Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane

AD Number
68-25-04
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Unknown
FR Citation
This information is not available.

Applicability

TypeManufacturerModelDetails
aircraft Vickers-Armstrongs (Aircraft Limited) Viscount 744 Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane
aircraft Vickers-Armstrongs (Aircraft Limited) Viscount 745D Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane
aircraft Vickers-Armstrongs (Aircraft Limited) Viscount 810 Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane

Unsafe Condition

Fatigue failure of the nose wheel steering twin relief valve, P/N 70026 Sh. 35 at the valve body halves P/N 70026, Part 251 and Part 253.

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

Required Actions

Inspect valve body halves for cracks at the fluid transfer holes using dye penetrant method per specified technical leaflets. Replace valve body halves if cracks are found before further flight or according to time-in-service thresholds. Replace with inspected/crack-free or new P/N 70026-637-639 parts.

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

Compliance Time

Compliance required as indicated unless already accomplished. Specific timelines depend on valve's time-in-service hours as of AD effective date: inspections and replacements must be done within specified intervals (e.g., prior to 15,000 hours, within next 350 hours, etc.) based on existing time-in-service.

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

Affected Aircraft

Vickers-Armstrongs (Aircraft Limited) Viscount Models 744, 745D, and 810 Series airplanes.

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

Federal Register Abstract

Nose Steering Relief Valve

Applicability Source Text

Show captured applicability text from the source AD
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AD Number:
68-25-04
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane
Subject:
Nose Steering Relief Valve
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
01/07/1969
Make:
Vickers-Armstrongs (Aircraft Limited)
Model:
Viscount 744 | Viscount 745D | Viscount 810
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: 68-25-04
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-691

AD NUMBER:   68-25-04

SUBJECT HEADING:   Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane

ACTION:  

SUMMARY:  

DATES:   Effective January 7, 1969.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
68-25-04 VICKERS: Amendment 39-691. Applies to Viscount Models 744, 745D and 810 Series Airplane.

Compliance required as indicated unless already accomplished.

To prevent fatigue failure of the nose wheel steering twin relief valve, P/N 70026 Sh. 35 at the valve body halves P/N 70026, Part 251 and Part 253, accomplish the following:

(a) Inspect the valve body halves as specified in paragraph (b) at the following times:

(1) Valves having less than 14,650 hours time in service on the effective date of the AD must be inspected prior to the accumulation of 15,000 hours time in service and thereafter at intervals not to exceed 2500 hours time in service.

(2) Valves that have accumulated 14,650 or more but less than 20,000 hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service and thereafter at intervals not to exceed 2500 hours time in service.

(3) Valves that have accumulated 20,000 or more but less that 22,800 hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service and thereafter at intervals not to exceed 1000 hours time in service.

(4) Valves that have accumulated 22,800 or more hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service.

(b) Inspect the valve body halves for cracks at the fluid transfer holes by a dye penetrant method in accordance with British Aircraft Corporation Viscount Preliminary Technical Leaflet No. 265 Issue 2 (700 Series) or No. 128 Issue 2 (810 Series) or later ARB approved issue or an FAA approved equivalent.

(c) Replace the valve body halves in accordance with paragraph (d) at the following times:

(1) If cracks are found during the inspections required by paragraph (a), replace the valve body halves prior to further flight.

(2) If no cracks are found during the inspections required by paragraph (a), replace the valve body halves as follows:

(i) Valves having less than 14,650 hours time in service on the effective date of this AD, must be replaced before the accumulation of 20,000 hours time in service.

(ii) Valves having 14,650 or more but less than 22,800 hours time in service on the effective date of this AD must be replaced before the accumulation of 23,500.

(iii) Valves having 22,800 or more hours time in service on the effective date of this AD must be replaced within the next 750 hours time in service after the effective date of this AD.

(d) Replace valve body halves with parts having the same part numbers which have been inspected and found to have no cracks or with new valve body halves P/N 70026-637-639.

(e) Valves of the same part numbers used as replacements must continue to be inspected in accordance with paragraph (a) and replaced in accordance with paragraph (c). Compliance with the inspection and replacement requirements of this AD may be discontinued when new valves P/N 70026-637-639 are incorporated.

This amendment becomes effective January 7, 1969.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_68-25-04.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
68-25-04
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane
Subject:
Nose Steering Relief Valve
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
01/07/1969
Make:
Vickers-Armstrongs (Aircraft Limited)
Model:
Viscount 744 | Viscount 745D | Viscount 810
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: 68-25-04
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-691

AD NUMBER:   68-25-04

SUBJECT HEADING:   Airworthiness Directives; VICKERS Models 744, 745D and 810 Series Airplane

ACTION:  

SUMMARY:  

DATES:   Effective January 7, 1969.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
68-25-04 VICKERS: Amendment 39-691. Applies to Viscount Models 744, 745D and 810 Series Airplane.

Compliance required as indicated unless already accomplished.

To prevent fatigue failure of the nose wheel steering twin relief valve, P/N 70026 Sh. 35 at the valve body halves P/N 70026, Part 251 and Part 253, accomplish the following:

(a) Inspect the valve body halves as specified in paragraph (b) at the following times:

(1) Valves having less than 14,650 hours time in service on the effective date of the AD must be inspected prior to the accumulation of 15,000 hours time in service and thereafter at intervals not to exceed 2500 hours time in service.

(2) Valves that have accumulated 14,650 or more but less than 20,000 hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service and thereafter at intervals not to exceed 2500 hours time in service.

(3) Valves that have accumulated 20,000 or more but less that 22,800 hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service and thereafter at intervals not to exceed 1000 hours time in service.

(4) Valves that have accumulated 22,800 or more hours time in service on the effective date of this AD must be inspected within the next 350 hours time in service.

(b) Inspect the valve body halves for cracks at the fluid transfer holes by a dye penetrant method in accordance with British Aircraft Corporation Viscount Preliminary Technical Leaflet No. 265 Issue 2 (700 Series) or No. 128 Issue 2 (810 Series) or later ARB approved issue or an FAA approved equivalent.

(c) Replace the valve body halves in accordance with paragraph (d) at the following times:

(1) If cracks are found during the inspections required by paragraph (a), replace the valve body halves prior to further flight.

(2) If no cracks are found during the inspections required by paragraph (a), replace the valve body halves as follows:

(i) Valves having less than 14,650 hours time in service on the effective date of this AD, must be replaced before the accumulation of 20,000 hours time in service.

(ii) Valves having 14,650 or more but less than 22,800 hours time in service on the effective date of this AD must be replaced before the accumulation of 23,500.

(iii) Valves having 22,800 or more hours time in service on the effective date of this AD must be replaced within the next 750 hours time in service after the effective date of this AD.

(d) Replace valve body halves with parts having the same part numbers which have been inspected and found to have no cracks or with new valve body halves P/N 70026-637-639.

(e) Valves of the same part numbers used as replacements must continue to be inspected in accordance with paragraph (a) and replaced in accordance with paragraph (c). Compliance with the inspection and replacement requirements of this AD may be discontinued when new valves P/N 70026-637-639 are incorporated.

This amendment becomes effective January 7, 1969.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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