AD 70-08-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61A | Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters |
Unsafe Condition
Combustion air inlet duct backfire check valve (Bobrick Co. P/N 9660-1-1 or 40064-32) may have distortion, missing flappers, or other obvious damage leading to fuel contamination or heater system failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect the combustion air inlet duct backfire check valve for distortion, missing flappers, or damage within the next 10 heater hours in service, and every 15 heater hours thereafter. Replace defective valves before further heater operation and inspect heater inlet ducting for fuel contamination, which must be eliminated before further heater use.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 10 heater hours in service, and every 15 heater hours in service thereafter. Compliance time may be based on helicopter hours in service if heater operating time cannot be documented.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Models S-61A, S-61L, S-61N, and S-61R helicopters certificated in all categories.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Heater Inlet Check Valve
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_70-08-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-08-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters Subject: Heater Inlet Check Valve Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 03/17/1970 Make: Sikorsky Aircraft Corporation Model: S-61A | S-61L | S-61N | S-61R 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: 70-08-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-974 AD NUMBER: 70-08-03 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters ACTION: SUMMARY: DATES: Effective April 23, 1970, and was effective March 17, 1970 for all recipients of the telegram. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-08-03 SIKORSKY: Amdt. 39-974. Applies to Sikorsky type S-61A/L/N/R helicopters certificated in all categories. Accomplish the following within the next 10 heater hours in service, unless already accomplished, and every 15 heater hours in service thereafter: A. Remove and inspect combustion air inlet duct backfire check valve Bobrick Co. P/N 9660-1-1 or 40064-32 for distortion, missing flappers, or other obvious damage. B. Replace defective valves before further operation of the heater with a part inspected in accordance with paragraph A above. Upon replacement inspect all heater inlet air ducting for evidence of fuel contamination. Any fuel contamination must be eliminated before further heater operation. C. Upon submission of substantiating data through an FAA maintenance inspector, the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator. D. For the purpose of this AD, compliance time may be based on helicopter hours in service if the owner or operator cannot document heater operating time. This amendment is effective April 23, 1970, and was effective March 17, 1970 for all recipients of the telegram dated March 17, 1970 which contained this amendment. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_70-08-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-08-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters Subject: Heater Inlet Check Valve Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 03/17/1970 Make: Sikorsky Aircraft Corporation Model: S-61A | S-61L | S-61N | S-61R 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: 70-08-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-974 AD NUMBER: 70-08-03 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61A, S-61L, S-61N, and S-61R Helicopters ACTION: SUMMARY: DATES: Effective April 23, 1970, and was effective March 17, 1970 for all recipients of the telegram. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-08-03 SIKORSKY: Amdt. 39-974. Applies to Sikorsky type S-61A/L/N/R helicopters certificated in all categories. Accomplish the following within the next 10 heater hours in service, unless already accomplished, and every 15 heater hours in service thereafter: A. Remove and inspect combustion air inlet duct backfire check valve Bobrick Co. P/N 9660-1-1 or 40064-32 for distortion, missing flappers, or other obvious damage. B. Replace defective valves before further operation of the heater with a part inspected in accordance with paragraph A above. Upon replacement inspect all heater inlet air ducting for evidence of fuel contamination. Any fuel contamination must be eliminated before further heater operation. C. Upon submission of substantiating data through an FAA maintenance inspector, the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator. D. For the purpose of this AD, compliance time may be based on helicopter hours in service if the owner or operator cannot document heater operating time. This amendment is effective April 23, 1970, and was effective March 17, 1970 for all recipients of the telegram dated March 17, 1970 which contained this amendment. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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