AD 73-07-05

final rule

Airworthiness Directives; McKinnon Model G-21 Series Airplanes

AD Number
73-07-05
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 Atlantic Coast Seaplanes LLC G-21C Airworthiness Directives; McKinnon Model G-21 Series Airplanes
aircraft Atlantic Coast Seaplanes LLC G-21D Airworthiness Directives; McKinnon Model G-21 Series Airplanes
aircraft Atlantic Coast Seaplanes LLC G-21E Airworthiness Directives; McKinnon Model G-21 Series Airplanes
aircraft Atlantic Coast Seaplanes LLC G-21G Airworthiness Directives; McKinnon Model G-21 Series Airplanes

Unsafe Condition

Failure of the elevator or rudder torque tubes due to cracks or corrosion could cause hazards in flight.

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

Required Actions

Inspect torque tubes for cracks or corrosion and repair or replace as needed. For assemblies with over 6000 hours or 7 years, inspect support tubes for corrosion, remove and inspect bellcranks, arms, pedals for corrosion/cracking, discard specific torque tubes and install new ones, then reassemble and restart inspection program. Allow flight to repair location under FAR 21.197 if corroded but uncracked.

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

Compliance Time

Within one (1) month after the effective date of this AD, and at intervals not to exceed twelve (12) months from last inspection for applicable assemblies. For those with over 6000 hours or 7 years, within the next year.

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

Affected Aircraft

Atlantic Coast Seaplanes LLC Model G-21C, G-21D, G-21E, G-21G with torque tube assemblies (Gruman Part Numbers 12755-1, 12756-1, 12757-1, 12758-1) and support tubes (Part Numbers 12725-1 and -2).

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

Federal Register Abstract

Elevator or Rudder Torque Tube Assys

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_73-07-05.html
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AD Number:
73-07-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; McKinnon Model G-21 Series Airplanes
Subject:
Elevator or Rudder Torque Tube Assys
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Atlantic Coast Seaplanes LLC
Model:
G-21C | G-21D | G-21E | G-21G
Product Type:
Aircraft
Product Subtype:
Small 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: 73-07-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-1614

AD NUMBER:   73-07-05

SUBJECT HEADING:   Airworthiness Directives; McKinnon Model G-21 Series Airplanes

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:   73-07-05 McKINNON: Amdt. 39-1614. Applies to Model G-21 Series 73-07-05 McKinn Airplanes.
Compliance required as indicated.
Applicable to torque tube assemblies, Gruman Part Numbers 12755-1, 12756-1, 12757-1, and 12758-1, and the support tubes, Part Numbers 12725-1 and -2.
A. Applicable to those torque tube and support tube assemblies having less than 6000 hours' time in service, or less than 7 years' life since re-manufacture:
To prevent hazards in flight associated with the failure of the elevator or rudder torque tubes, unless already accomplished within the last eleven (11) months, visually inspect the external condition of the tubes within one (1) month after the effective date of this AD, and at intervals thereafter not to exceed twelve (12) months from last inspection. Tubes which are cracked or show evidence of corrosion must either be repaired or replaced in accordance with FAR Part 43 and Advisory Circular 43.13-1 prior to further flight.
B. Applicable to those torque tube and support tube assemblies having more than 6000 hours' time in service, or more than 7 years since re-manufacture. Within the next year, unless already accomplished:
(1) Visually inspect the support tubes, Part Numbers 12725-1 and -2 for corrosion. If corrosion is found, repair or replace in accordance with FAR Part 43 and Advisory Circular 43.13-1 before further flight.
(2) Remove all bolted bellcranks, arms, and pedals from the torque tubes. Using visual and dye penetrant methods, or an FAA-approved equivalent inspection, inspect the parts removed from the torque tubes for corrosion and cracking. Repair and replace in accordance with FAR Part 43 and AC 43.13-1.
(3) Discard elevator torque tube, Part Number 12755-1; rudder torque tube, Part Number 12756-1 and the L.H. and R.H. rudder pedal torque tubes, Part Numbers 12757-1 and 12758-1. Install new manufactured parts or fabricate replacement tubes in accordance with FAR 43 and AC 43.13-1 from new manufacture stock 2024-T3 (material specifications WW-T-700/3 or equivalent) in conformance with the above drawings taking special care to corrosion-proof the interior as well as the exterior surfaces of the tubes.
(4) Re-assemble and re-initiate the visual inspection program per (A) until reaching the rebuild threshold per (B).
C. Aircraft with badly corroded but uncracked torque tubes may be flown in accordance with FAR 21.197 to a base where a repair or replacement can be performed.
D. Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, may adjust the repetitive inspection intervals specified in this AD.
This supersedes Amendment 39-1525 (31 F.R. 13697), AD 72-20-04.
This Amendment becomes effective on publication.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_73-07-05.html
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Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
73-07-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; McKinnon Model G-21 Series Airplanes
Subject:
Elevator or Rudder Torque Tube Assys
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Atlantic Coast Seaplanes LLC
Model:
G-21C | G-21D | G-21E | G-21G
Product Type:
Aircraft
Product Subtype:
Small 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: 73-07-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-1614

AD NUMBER:   73-07-05

SUBJECT HEADING:   Airworthiness Directives; McKinnon Model G-21 Series Airplanes

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:   73-07-05 McKINNON: Amdt. 39-1614. Applies to Model G-21 Series 73-07-05 McKinn Airplanes.
Compliance required as indicated.
Applicable to torque tube assemblies, Gruman Part Numbers 12755-1, 12756-1, 12757-1, and 12758-1, and the support tubes, Part Numbers 12725-1 and -2.
A. Applicable to those torque tube and support tube assemblies having less than 6000 hours' time in service, or less than 7 years' life since re-manufacture:
To prevent hazards in flight associated with the failure of the elevator or rudder torque tubes, unless already accomplished within the last eleven (11) months, visually inspect the external condition of the tubes within one (1) month after the effective date of this AD, and at intervals thereafter not to exceed twelve (12) months from last inspection. Tubes which are cracked or show evidence of corrosion must either be repaired or replaced in accordance with FAR Part 43 and Advisory Circular 43.13-1 prior to further flight.
B. Applicable to those torque tube and support tube assemblies having more than 6000 hours' time in service, or more than 7 years since re-manufacture. Within the next year, unless already accomplished:
(1) Visually inspect the support tubes, Part Numbers 12725-1 and -2 for corrosion. If corrosion is found, repair or replace in accordance with FAR Part 43 and Advisory Circular 43.13-1 before further flight.
(2) Remove all bolted bellcranks, arms, and pedals from the torque tubes. Using visual and dye penetrant methods, or an FAA-approved equivalent inspection, inspect the parts removed from the torque tubes for corrosion and cracking. Repair and replace in accordance with FAR Part 43 and AC 43.13-1.
(3) Discard elevator torque tube, Part Number 12755-1; rudder torque tube, Part Number 12756-1 and the L.H. and R.H. rudder pedal torque tubes, Part Numbers 12757-1 and 12758-1. Install new manufactured parts or fabricate replacement tubes in accordance with FAR 43 and AC 43.13-1 from new manufacture stock 2024-T3 (material specifications WW-T-700/3 or equivalent) in conformance with the above drawings taking special care to corrosion-proof the interior as well as the exterior surfaces of the tubes.
(4) Re-assemble and re-initiate the visual inspection program per (A) until reaching the rebuild threshold per (B).
C. Aircraft with badly corroded but uncracked torque tubes may be flown in accordance with FAR 21.197 to a base where a repair or replacement can be performed.
D. Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, may adjust the repetitive inspection intervals specified in this AD.
This supersedes Amendment 39-1525 (31 F.R. 13697), AD 72-20-04.
This Amendment becomes effective on publication.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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