AD 49-47-02

final rule

Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters

AD Number: 49-47-02
Status: final_rule
Effective Date: N/A
Product Category: aircraft
Docket: Unknown
FR Citation: This information is not available.

Technical illustration of a helicopter rotor hub assembly — Problem area **Rotor system**

Applicability

Type	Manufacturer	Model	Details
aircraft	Scotts-Bell 47 Inc	47B	Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters
aircraft	Scotts-Bell 47 Inc	47B3	Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters
aircraft	Scotts-Bell 47 Inc	47D	Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters
aircraft	Scotts-Bell 47 Inc	47D1	Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters

Unsafe Condition

Failures of the tail rotor drive system, including wear, cracks, chips, brinelling, dents, cuts, fatigue signs, and cracks at thread roots of the sleeve, could result in loss of tail rotor drive function.

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

Required Actions

Inspect bearings, shaft surfaces, and sleeve for wear, cracks, chips, brinelling, dents, cuts, fatigue signs, and cracks at thread roots via visual and magnaflux inspections every 50 hours starting with the next 25 hours of operation. Install redesigned drive shafts (P/N 47-644-126, 47-644-181) and spline couplings (P/N 47-644-177, 47-644-130) by February 15, 1950.

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

Compliance Time

Not later than the next 25 hours of operation and at each 50-hour period thereafter until modifications are incorporated. Modifications must be completed by February 15, 1950.

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

Affected Aircraft

Scotts-Bell 47 Inc Model 47B, 47B3, 47D, and Model 47D1 serial numbers 145 through 164.

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

Federal Register Abstract

Tail Rotor Drive Shaft

Applicability Source Text

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Details
AD Number:
49-47-02
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters
Subject:
Tail Rotor Drive Shaft
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Scotts-Bell 47 Inc
Model:
47B | 47B3 | 47D | 47D1
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: 49-47-02
CITATION: This information is not available.

PAGE NUMBER:

DOCKET NUMBER: Unknown

AMENDMENT:

AD NUMBER: 49-47-02

SUBJECT HEADING: Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters

ACTION:

SUMMARY:

DATES:

ADDRESSES:

FOR FURTHER INFORMATION CONTACT:

SUPPLEMENTARY INFORMATION:

REGULATORY TEXT:
49-47-02 BELL: Applies to All Models 47B, 47B3, 47D, and Model 47D1 Serial Numbers 145 Through 164.

Compliance as indicated.

As a result of recent failures occurring to the tail rotor drive system the following inspections and replacements must be accomplished:

1. Not later than the next 25 hours of operation and at each 50-hour period thereafter the following inspection procedure must be accomplished until the tail rotor drive shaft parts as described below are incorporated:

(a) Remove and disassemble tail boom extension for complete inspection.

(b) Visually inspect bearings for wear, cracks, chips, and brinelling.

(d) Conduct a magnaflux inspection of the tail boom extension drive shaft, examining particularly the shaft surface for approximately 3 inches of length from each end of the shaft.

(e) Magnaflux 47-644-C14 sleeve inspecting for cracks at thread roots closest to flange.

2. To compensate for shaft misalignment and flight distortion of the shaft assembly, the following modifications shall be accomplished not later than February 15, 1950:

(a) Installation of a redesigned extension drive shaft P/N 47-644-126 and 47- 644-181.

(b) Installation of a spline coupling in tail rotor drive shaft forward of the universal joint P/N 47-644-177 and 47-644-130.

(Bell Service Bulletin No. 69, dated November 11, 1949, covers this subject.)

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