AD 86-16-11 L

final rule

Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters

AD Number
86-16-11 L
Status
final_rule
Effective Date
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

TypeManufacturerModelDetails
aircraft Bell Helicopter Textron, Inc. 412 Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters

Unsafe Condition

Failure of the tail rotor control due to cracks in the T/R trunnion housing P/N 212-011-716-1 or axial play in the T/R trunnion, or presence of excess balance washers.

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

Required Actions

Visually inspect the T/R hub assembly P/N 212-011-701-3 per Part I of BHTI ASB 412-86-25. If cracks, axial play, or excess washers exist, perform Part II of the ASB before further flight. Repeat inspections every 20 hours' time in service until paragraph (b) is done. Inspect trunnion bearing housing P/N 212-011-716-1 per Part II of the ASB within 150 hours' time in service or 60 days after AD issue, replacing housings with end web thickness ≤0.059 inches.

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

Compliance Time

Within 20 hours' time in service after receipt of this AD for initial inspection. For paragraph (b), within 150 hours' time in service or within 60 days after the issue date of this AD, whichever occurs first.

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

Affected Aircraft

Bell Helicopter Textron, Inc. Model 412 helicopters, serial numbers 33001 through 33118, 33120 and 33121, certified in any category.

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

Federal Register Abstract

Inspect T/R Hub Assembly (See 90-03-09)

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_86-16-11_L.html
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AD Number:
86-16-11 L
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters
Subject:
Inspect T/R Hub Assembly (See 90-03-09)
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Bell Helicopter Textron, Inc.
Model:
412
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: 86-16-11 L
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   86-16-11 L

SUBJECT HEADING:   Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
86-16-11 BELL HELICOPTER TEXTRON, INC.: Letter issued August 12, 1986. Applies to all Bell Helicopter Model 412 helicopters, S/N 33001 through 33118, 33120 and 33121, certified in any category.

Compliance required as indicated unless already accomplished.

To prevent failure of the tail rotor control, accomplish the following:

(a) Within 20 hours' time in service after receipt of this AD, visually inspect the T/R hub assembly P/N 212-011-701-3, in accordance with Part I of Bell Helicopter Textron, Inc. (BHTI), Alert Service Bulletin (ASB) 412-86-25, Revision "A," dated July 23,1986.

(1) If the (P/N) 212-011-716-1 T/R trunnion housing is cracked or there is axial play in the T/R trunnion, or if there are excess balance washers, comply with Part II of the Alert Service Bulletin before further flight.

(2) Repeat this inspection every 20 hours' time in service until paragraph (b) of this AD is accomplished.

(b) Remove the 212-011-701-1 T/R hub and blade assembly and inspect the trunnion bearing housing, P/N 212-011-716-1, as detailed in Part II of BHTI ASB 412-86-25, Revision "A," dated July 23, 1986, within 150 hours' time in service or within 60 days after the issue date of this AD, whichever occurs first. Replace any housing having an end web thickness of .059 inches or less with a serviceable part.

An alternate method of compliance or adjustment of the compliance time, which provides an equivalent level of safety, may be approved by the Manager, Helicopter Certification Branch, Aircraft Certification Division, FAA, Southwest Region.

This airworthiness directive becomes effective upon receipt.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_86-16-11_L.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
86-16-11 L
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters
Subject:
Inspect T/R Hub Assembly (See 90-03-09)
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Bell Helicopter Textron, Inc.
Model:
412
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: 86-16-11 L
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   86-16-11 L

SUBJECT HEADING:   Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 412 Helicopters

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
86-16-11 BELL HELICOPTER TEXTRON, INC.: Letter issued August 12, 1986. Applies to all Bell Helicopter Model 412 helicopters, S/N 33001 through 33118, 33120 and 33121, certified in any category.

Compliance required as indicated unless already accomplished.

To prevent failure of the tail rotor control, accomplish the following:

(a) Within 20 hours' time in service after receipt of this AD, visually inspect the T/R hub assembly P/N 212-011-701-3, in accordance with Part I of Bell Helicopter Textron, Inc. (BHTI), Alert Service Bulletin (ASB) 412-86-25, Revision "A," dated July 23,1986.

(1) If the (P/N) 212-011-716-1 T/R trunnion housing is cracked or there is axial play in the T/R trunnion, or if there are excess balance washers, comply with Part II of the Alert Service Bulletin before further flight.

(2) Repeat this inspection every 20 hours' time in service until paragraph (b) of this AD is accomplished.

(b) Remove the 212-011-701-1 T/R hub and blade assembly and inspect the trunnion bearing housing, P/N 212-011-716-1, as detailed in Part II of BHTI ASB 412-86-25, Revision "A," dated July 23, 1986, within 150 hours' time in service or within 60 days after the issue date of this AD, whichever occurs first. Replace any housing having an end web thickness of .059 inches or less with a serviceable part.

An alternate method of compliance or adjustment of the compliance time, which provides an equivalent level of safety, may be approved by the Manager, Helicopter Certification Branch, Aircraft Certification Division, FAA, Southwest Region.

This airworthiness directive becomes effective upon receipt.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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