AD 71-21-10

final rule

Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Categories in Which A Microdot, Inc. Model 1410 Cockpit Voice Recorder is Installed

AD Number
71-21-10
Status
final_rule
Effective Date
Product Category
appliance
Docket
Unknown
FR Citation
This information is not available.

Applicability

TypeManufacturerModelDetails
aircraft Microdot Cockpit Voice Recorder Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Categories in Which A Microdot, Inc. Model 1410 Cockpit Voice Recorder is Installed
appliance Microdot Cockpit Voice Recorder Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Categories in Which A Microdot, Inc. Model 1410 Cockpit Voice Recorder is Installed

Unsafe Condition

Inadvertent visual test circuit light illumination and reliance by flight crew members thereon.

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

Required Actions

Remove the test light bulb from the CVR Control Unit and install a placard stating 'TEST LIGHT INOPERATIVE'. Perform a daily aural functional test using a 600 ohm headset, checking for satisfactory speech reproduction after a one-second delay. Replace the bulb and remove the placard once Microdot Service Bulletin No. 4-A or equivalent modification is installed.

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

Compliance Time

Within five days of the effective date of this AD

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

Affected Aircraft

All civil aircraft certificated in all categories in which a Microdot, Inc. Model 1410 Cockpit Voice Recorder is installed.

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

Federal Register Abstract

Cockpit Voice Recorder

Applicability Source Text

Show captured applicability text from the source AD
AD Final Rules - DRS_71-21-10.html
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AD Number:
71-21-10
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Catego...Show more
Subject:
Cockpit Voice Recorder
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
10/13/1971
Make:
Microdot
Model:
Cockpit Voice Recorder
Product Type:
Appliance
Product Subtype:
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 71-21-10
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-1316

AD NUMBER:   71-21-10

SUBJECT HEADING:   Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Categories in Which A Microdot, Inc. Model 1410 Cockpit Voice Recorder is Installed

ACTION:  

SUMMARY:  

DATES:   Effective October 13, 1971.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
71-21-10 MICRODOT, INC.: Amendment 39-1316. Applies to all civil aircraft certificated in all categories in which a Microdot, Inc. Model 1410 Cockpit Voice Recorder is installed.

Compliance required as indicated.

To prevent inadvertent visual test circuit light illumination and reliance by flight crew members thereon, accomplish the following:

(a) Within five days of the effective date of this AD.,

(1) Remove the test light bulb from the CVR Control Unit and install a placard on the face of the CVR Control Unit adjacent to the test light thereon, which reads: TEST LIGHT INOPERATIVE, and

(2) Perform the following aural functional test (in lieu of the visual functional test) at least once each day during which the aircraft is flown:

(i) Plug low impedance headset (600 ohms) into the CVR audio jack, or into the CVR Control Unit audio jack, if connected.

(ii) Speak into the area microphone, or apply a speech signal to the CVR from any other monitored source.

(iii) Determine that recorded speech is satisfactorily reproduced in the headset (after a delay of approximately one second).

(b) The test light bulb should be replaced, the placard should be removed, and the aural functional test required by (a) above, may be discontinued after accomplishment of the modification described in Microdot, Inc. Service Bulletin No. 4-A, dated 14 September 1971, or later FAA approved revisions, or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA Western Region. This modification, when installed, will constitute terminating action under this AD.

This amendment becomes effective on October 13, 1971.

FOOTER:

Document Text

Show stored source text (verify against official source)
AD Final Rules - DRS_71-21-10.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
71-21-10
Document Type:
AD Final Rules
Docket Number:
Unknown
Subject Heading:
Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Catego...Show more
Subject:
Cockpit Voice Recorder
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
10/13/1971
Make:
Microdot
Model:
Cockpit Voice Recorder
Product Type:
Appliance
Product Subtype:
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 71-21-10
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   Unknown

AMENDMENT:   39-1316

AD NUMBER:   71-21-10

SUBJECT HEADING:   Airworthiness Directives; MICRODOT, INC.: Applies to all Civil Aircraft Certificated in all Categories in Which A Microdot, Inc. Model 1410 Cockpit Voice Recorder is Installed

ACTION:  

SUMMARY:  

DATES:   Effective October 13, 1971.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
71-21-10 MICRODOT, INC.: Amendment 39-1316. Applies to all civil aircraft certificated in all categories in which a Microdot, Inc. Model 1410 Cockpit Voice Recorder is installed.

Compliance required as indicated.

To prevent inadvertent visual test circuit light illumination and reliance by flight crew members thereon, accomplish the following:

(a) Within five days of the effective date of this AD.,

(1) Remove the test light bulb from the CVR Control Unit and install a placard on the face of the CVR Control Unit adjacent to the test light thereon, which reads: TEST LIGHT INOPERATIVE, and

(2) Perform the following aural functional test (in lieu of the visual functional test) at least once each day during which the aircraft is flown:

(i) Plug low impedance headset (600 ohms) into the CVR audio jack, or into the CVR Control Unit audio jack, if connected.

(ii) Speak into the area microphone, or apply a speech signal to the CVR from any other monitored source.

(iii) Determine that recorded speech is satisfactorily reproduced in the headset (after a delay of approximately one second).

(b) The test light bulb should be replaced, the placard should be removed, and the aural functional test required by (a) above, may be discontinued after accomplishment of the modification described in Microdot, Inc. Service Bulletin No. 4-A, dated 14 September 1971, or later FAA approved revisions, or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA Western Region. This modification, when installed, will constitute terminating action under this AD.

This amendment becomes effective on October 13, 1971.

FOOTER:

Source: Official FAA Source ↗

Retrieved: Apr 8, 2026

Rights: U.S. Government Public Domain

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