AD 56-20-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Kelowna Flightcraft R & D Ltd. | 240 Series | CONVAIR Model 240, 340 and 440 Aircraft |
| aircraft | Kelowna Flightcraft R & D Ltd. | 340 | CONVAIR Model 240, 340 and 440 Aircraft |
| aircraft | Kelowna Flightcraft R & D Ltd. | 440 | CONVAIR Model 240, 340 and 440 Aircraft |
Unsafe Condition
Deficiencies in the construction of fire seals between zone 1 and zone 2 nacelle areas, leading to nacelle fires as indicated by recent accidents.
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Required Actions
Incorporate an additional fireproof seal at the zone 1 to zone 2 shroud-to-cowl seal, improve nacelle seals with fireproof material along cowl segment junctures and hinge points, and replace aluminum chimney vent material with steel (CV-240 only).
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Compliance Time
Not later than December 31, 1957, or at the next engine change or airplane overhaul, whichever comes first.
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Affected Aircraft
Convair Model 240, 340, and 440 aircraft, all serial numbers.
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Federal Register Abstract
Fire Seals
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_56-20-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-20-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: CONVAIR Model 240, 340 and 440 Aircraft Subject: Fire Seals Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Kelowna Flightcraft R & D Ltd. Model: 240 Series | 340 | 440 Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 56-20-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-20-04 SUBJECT HEADING: CONVAIR Model 240, 340 and 440 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-20-04 CONVAIR: Applies to All 240, 340 and 440 Aircraft. Compliance recommended at the next engine change or airplane overhaul but required not later than December 31, 1957. Several recent accidents involving nacelle fires have indicated certain deficiencies in the construction of the fire seals between zone 1 and zone 2. To correct this condition the following rework of the present cowling and zone seals is required. 1. Incorporate an additional fireproof seal at the zone 1 to zone 2 shroud-to-cowl seal around the periphery of the diaphragm where the bottom and side cowl meet. 2. Improve the present nacelle seals by incorporating a fireproof seal along the longitudinal juncture of the cowl segments and also improve the present cowl hinge point seals. 3. Replace any existing aluminum material in the zone 2 chimney vent with steel material. (Applicable to CV-240 aircraft only.) The following Convair Service Bulletins cover acceptable methods of compliance with these modifications: Nos. 240-472 and 340-177 cover item No. 1; Nos. 240-474, 240-481A, 340- 209, 340-210A, 440-30 and 440-32A cover item No. 2; Nos. 240-470 and Revision 1 cover item No. 3. (Compliance with Revision 2 to 240-470 is not required.) FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_56-20-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-20-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: CONVAIR Model 240, 340 and 440 Aircraft Subject: Fire Seals Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Kelowna Flightcraft R & D Ltd. Model: 240 Series | 340 | 440 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: 56-20-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-20-04 SUBJECT HEADING: CONVAIR Model 240, 340 and 440 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-20-04 CONVAIR: Applies to All 240, 340 and 440 Aircraft. Compliance recommended at the next engine change or airplane overhaul but required not later than December 31, 1957. Several recent accidents involving nacelle fires have indicated certain deficiencies in the construction of the fire seals between zone 1 and zone 2. To correct this condition the following rework of the present cowling and zone seals is required. 1. Incorporate an additional fireproof seal at the zone 1 to zone 2 shroud-to-cowl seal around the periphery of the diaphragm where the bottom and side cowl meet. 2. Improve the present nacelle seals by incorporating a fireproof seal along the longitudinal juncture of the cowl segments and also improve the present cowl hinge point seals. 3. Replace any existing aluminum material in the zone 2 chimney vent with steel material. (Applicable to CV-240 aircraft only.) The following Convair Service Bulletins cover acceptable methods of compliance with these modifications: Nos. 240-472 and 340-177 cover item No. 1; Nos. 240-474, 240-481A, 340- 209, 340-210A, 440-30 and 440-32A cover item No. 2; Nos. 240-470 and Revision 1 cover item No. 3. (Compliance with Revision 2 to 240-470 is not required.) FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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