AD 76-21-05

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AD Number:
76-21-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Bell Model 47K Helicopters
Subject:
Tubular Spar at Elevators
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
11/26/1976
Make:
Scotts-Bell 47 Inc
Model:
47K
Product Type:
Aircraft
Product Subtype:
Rotorcraft
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 76-21-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-2749

AD NUMBER:   76-21-05

SUBJECT HEADING:   Airworthiness Directives; Bell Model 47K Helicopters

ACTION:  

SUMMARY:  

DATES:   Effective November 26, 1976.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
76-21-05 BELL: Amendment 39-2749. Applies to Bell Model 47K helicopters certificated in all categories.

Compliance required as indicated.

A report has been received of fatigue cracking of the tubular spar of the synchronized elevator at the rollpin hole. To preclude possible separation of the elevator from the helicopter, accomplish the following:

(a) Within 25 hours' time in service after the effective date of this AD:

(1) Remove the elevators from the tail boom in accordance with the Bell Maintenance Manual.

(2) Clean the area around the Rollpin hole and remove any zinc chromate putty from any plugged hole in the tubular spar at B.L. 7.0 for both right and left elevators.

(3) Inspect for cracks in the tubular spar of both elevators at the Rollpin hole at B.L. 7.0 using a 5-power or higher magnifying glass.

(4) Inspect the inboard rib for cracks using a 5-power or higher magnifying glass.

(b) If cracks are found in the tubular spar, modify the elevator with Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator," or FAA engineering approved equivalent prior to further flight.

(c) If no cracks are found in the tubular spar, install clevis pin in accordance with subparagraphs (1) through (4) below or in accordance with item 2 of Bell Helicopter Company Service Bulletin No. 135SB dated July 27, 1961, or later approved revision, and reinspect in accordance with subparagraph (5).

(1) Position coupling assembly P/N 47-267-483-1 on elevators and line drill through Rollpin holes with a "D" (0.2460-inch diameter) drill. Remove sharp edges from holes. Install MS 20392-3-49 clevis pins, AN 960-4162 washers, and AN 381-3-6 cotter pins. A finger tight slip fit of the clevis pins is desired, approximately 0.0005 inch loose.

(2) Reinstall the elevator on the helicopter, shim as required to prevent preload or end play at bearings.

(3) Check clearance between skin and end of clevis pins. Trim skin, if necessary, to obtain clearance.

(4) Rerig elevator in accordance with the Bell Maintenance Manual.

(5) Reinspect in accordance with (a)(1) through (a)(3) within each succeeding 50 hours' time in service until Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator," or FAA approved equivalent is installed.

(d) If cracks are found in the inboard rib, repair the elevator as specified below, or modify with Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, or FAA engineering approved equivalent prior to further flight.

(1) Remove the inboard rib by drilling out the rivets and remove the Bell P/N 47-267-404-7 shoulder from the rib by drilling out the rivets.

(2) Add a doubler of 0.032 thickness, or a new rib of 0.032 thickness, material aluminum alloy 2024-0, or a Bell rib P/N 47-267-453-7 (one required per elevator).

(3) Rivet Bell P/N 47-267-404-1 shoulder to the old rib and new doubler or to the new rib. Use the rivet pattern in the shoulder with AN 470-AD3 or -4 rivets.

(4) Install the rib assembly, using the rivet pattern in the elevator skin with MS 20600 AD4 or -5 rivets.

(e) If no cracks are found in the inboard rib:

(1) Reinstall the elevator on the helicopter in accordance with Bell Maintenance Manual.

(2) Reinspect rib for cracks in accordance with (a)(4) within each succeeding 50 hours' time in service until Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator," or FAA engineering approved equivalent is installed.

(f) Upon request of the operator, an FAA maintenance inspector subject to prior approval of the Chief, Engineering and Manufacturing Branch, Southwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Service Manager, Bell Helicopter Company, Box 482, Fort Worth, Texas 76101. These documents may also be examined at Office of the Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas, and at FAA headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D.C., and at Office of Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas.

This amendment becomes effective November 26, 1976.

FOOTER: