AD 58-21-01

AD Final Rules - DRS_58-21-01.html
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AD Number:
58-21-01
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
LOCKHEED Models 049, 149, 649, 649A, 749, 749A, 1049- 54, 1049C, 1049D, 1049E, 1049G, 1049H, and 164...Show more
Subject:
Bulkhead Corrosion Inspection
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
Make:
Lockheed Aircraft Corporation | Lockheed Martin Aeronautics Company
Model:
1049-54 | 1049C-55 | 1049D-55 | 1049E-55 | 1049G-82 | 1049H-82 | 149-46 | 1649A-98 | 49-46 | 649-79 ...Show more
Product Type:
Aircraft
Product Subtype:
Large 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Superseded AD: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Superseded By: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: 58-21-01
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:  

AD NUMBER:   58-21-01

SUBJECT HEADING:   LOCKHEED Models 049, 149, 649, 649A, 749, 749A, 1049- 54, 1049C, 1049D, 1049E, 1049G, 1049H, and 1649 Aircraft

ACTION:  

SUMMARY:  

DATES:  

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
58-21-01 LOCKHEED: Applies to All Models 049, 149, 649, 649A, 749, 749A, 1049- 54, 1049C, 1049D, 1049E, 1049G, and 1049H and 1649 Aircraft.

Compliance required as indicated.

This is a supplement to AD 58-20-03, in that it applies to an additional area of the pressure bulkhead (Station 1037) and to a greater number of aircraft. A recent inspection of a Model 1049E airplane with 10,500 hours logged time revealed extensive corrosion along W.L. 239 (approximately) between a wood strip and pressure diaphragm at the lavatory seat level. Reported corroded area was approximately 27 inches long by 5 inches wide.

Accordingly, on all aircraft that have or once had lavatories in this area, accomplish the following:

1. Unless already accomplished per Lockheed wire FS/229080-W, within the next 50 flight hours thoroughly examine the aft side of the bulkhead for corrosion in the area of W.L. 239 from a height of 2 inches above to 2 inches below the centerline of rivet or screw attachments across the full width of the bulkhead. Probe the area with a blunt tool to detect advance stages of corrosion. If any evidence of corrosion is found, conduct inspection under step 3. immediately.

2. Unless already accomplished per Lockheed wire FS/229080-W, within 400 hours, inspect in accordance with step 3, or alternatively as follows:

Remove 5/8-inch maximum diameter slugs from the pressure diaphragm by means of a hole saw or equivalent method. Take samples at approximately 6- to 7-inch spacing from the back side of the bulkhead across its full width at approximately W.L. 239. Do not cut samples from diaphragm area covered by stiffeners. If samples show any evidence of corrosion, conduct inspection in accordance with step 3. immediately. Holes in diaphragm may be plugged in accordance with negligible damage repair shown in applicable structural repair manual.

3. If corrosion is found as a result of steps 1. or 2., the following inspections shall be conducted immediately. If both steps 1. and 2. reveal no corrosion, the following inspection shall be conducted at the next block overhaul or within 4,000 flight hours whichever occurs first and at each block overhaul or 4,000-hour period thereafter. Remove toilet seats and other portions of installation as required. Peel back trim and insulation to expose trim strip and at least 2 inches of bulkhead web above and below trim strip, completely across bulkhead within each lavatory compartment. Remove trim strip and all paint, sealant and cement from the exposed area of web. Make close visual inspection for corrosion.

4. Replace any material or parts which show evidence of corrosion damage. Strip to bare metal, apply inhibitor, sealant, and paint to all exposed web areas. In applying this protection, if the sealant and protective materials noted in Lockheed SB/597 are used, further special inspection at 4,000-hour intervals may be discontinued and normal routine inspections resumed.

5. If corrosion is found, flight operations shall be restricted, pending repairs as follows:

(a) Unpressurized flight is permissible if corrosion damage is found on the diaphragm as a result of inspection per steps 1. or 2.

(Lockheed wire FS/229080-W, dated October 13, 1958, covers the same subject as this supplement.) (Lockheed Structural Repair Manuals, as applicable, cover acceptable repair methods.)

FOOTER: