AD 47-33-05

final rule

Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft

AD Number
47-33-05
Status
final_rule
Effective Date
Product Category
aircraft
Docket
Unknown
FR Citation
This information is not available.
Technical illustration of a riveted aircraft structural panel and frame
Problem area Airframe structure

Applicability

TypeManufacturerModelDetails
aircraft Textron Aviation Inc. Army AT-11 Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft
aircraft Textron Aviation Inc. C18S Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft
aircraft Textron Aviation Inc. D18S Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft

Unsafe Condition

Cracks at the points of attachment of the horizontal stabilizer front spar and subspar to the fuselage, which could lead to structural failure.

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

Required Actions

Inspect the horizontal stabilizer front spar and subspar for cracks at attachment points to the fuselage. At each annual inspection, remove stabilizer and skin panel to check for cracks. If cracks are found, revise or replace the main spar with specific modifications, install dural channels and doubler, modify stabilizer-fuselage attaching angles, plug holes, and remove gang nut sections as specified.

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

Compliance Time

C18S and AT-11: prior to certification or next periodic inspection by November 1, 1947, then every 100 hours. D18S (serials prior to A-378): every 25 hours of normal operation or every 10 hours for transition/instrument training.

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

Affected Aircraft

Beech Models AT-11, C18S, and D18S (serial numbers prior to A-378)

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

Federal Register Abstract

Horizontal Stabilizer Spar

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_47-33-05.html
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AD Number:
47-33-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft
Subject:
Horizontal Stabilizer Spar
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Textron Aviation Inc.
Model:
Army AT-11 | C18S | D18S
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: 47-33-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   47-33-05

SUBJECT HEADING:   Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
47-33-05 BEECH: (Was Service Note 3 of AD-75777-2 and Service Note 1 of AD-765-1.) Applies to AT-11, C18S and D18S Aircraft.

C18S and AT-11 Airplanes: Inspection required prior to certification or, if certificated, on next periodic inspection but not later than November 1, 1947, and each 100 hours of operation thereafter.

D18S Airplanes (Serial Numbers prior to A-378): Inspection required each 25 hours of normal operation or each 10 hours where the airplane is flown for pilot's transition or instrument training.

Inspect the horizontal stabilizer front spar and subspar for cracks at the points of attachment to the fuselage. At each annual inspection remove stabilizer and the stabilizer lower front skin panel and check for evidence of cracks. If cracks are found the center section of the main spar must be revised or replaced with one having the lower flange-web radius cutout approximately 2 inches from either end. Two 0.064-inch dural channels (404-186053) should be installed between the new attachment fittings (437-186095 and 6) and the main spar web. At the main attachment fittings and 0.032-inch dural doubler (404-186052) should be riveted to the lower skin, the main spar, and the center nose rib flanges.

The forward part of the upper flanges of each stabilizer-fuselage attaching angle should be cut off as far back as the sixth screw hole. The corresponding 12 holes in the stabilizer should be plugged. A three-screw outboard section of the gang nut on each side of the stabilizer subspar should be removed and the corresponding holes in the No. 13 bulkhead angle plugged. The revision of the stabilizer attachments eliminates the necessity for further inspection for cracks except as made during the normal periodic inspection.

(Beech Service Bulletin No. D-18-48 revised April 1, 1948, covers this same subject.)

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_47-33-05.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
47-33-05
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft
Subject:
Horizontal Stabilizer Spar
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Textron Aviation Inc.
Model:
Army AT-11 | C18S | D18S
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: 47-33-05
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   47-33-05

SUBJECT HEADING:   Airworthiness Directives; Beech Models AT-11, C18S and D18S Aircraft

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
47-33-05 BEECH: (Was Service Note 3 of AD-75777-2 and Service Note 1 of AD-765-1.) Applies to AT-11, C18S and D18S Aircraft.

C18S and AT-11 Airplanes: Inspection required prior to certification or, if certificated, on next periodic inspection but not later than November 1, 1947, and each 100 hours of operation thereafter.

D18S Airplanes (Serial Numbers prior to A-378): Inspection required each 25 hours of normal operation or each 10 hours where the airplane is flown for pilot's transition or instrument training.

Inspect the horizontal stabilizer front spar and subspar for cracks at the points of attachment to the fuselage. At each annual inspection remove stabilizer and the stabilizer lower front skin panel and check for evidence of cracks. If cracks are found the center section of the main spar must be revised or replaced with one having the lower flange-web radius cutout approximately 2 inches from either end. Two 0.064-inch dural channels (404-186053) should be installed between the new attachment fittings (437-186095 and 6) and the main spar web. At the main attachment fittings and 0.032-inch dural doubler (404-186052) should be riveted to the lower skin, the main spar, and the center nose rib flanges.

The forward part of the upper flanges of each stabilizer-fuselage attaching angle should be cut off as far back as the sixth screw hole. The corresponding 12 holes in the stabilizer should be plugged. A three-screw outboard section of the gang nut on each side of the stabilizer subspar should be removed and the corresponding holes in the No. 13 bulkhead angle plugged. The revision of the stabilizer attachments eliminates the necessity for further inspection for cracks except as made during the normal periodic inspection.

(Beech Service Bulletin No. D-18-48 revised April 1, 1948, covers this same subject.)

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

This site is not affiliated with or endorsed by the FAA. Always verify with official sources.