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Service Letter No. 2724 Page 1 of 2Rev C 23 May 2002

No. 2724

Functional Equivalency of the CVR-80 withCVR-30, CVR-30A, CVR-30B or CVR-120

NOTE: Revision C to this Service Letter adds the conversion requirements for updating

the CVR-80 to a CVR-30B or CVR-120.

This letter discusses the functional equivalency between the Solid State CVR-30, CVR-30A,CVR-30B, CVR-120 and CVR-80.

The CVR-30 (P/N 1601-01-3, 1601-02-3) and CVR-80 (P/N 1600-01) were both designed to bein conformance with ARINC Specification 557 and TSO C84. Therefore, any aircraftinstallation which is wired for the CVR-80 will work properly if the correct (DC vs ACoperation) CVR-30 P/N is used. All accessory equipment (Cockpit Control Unit, Microphone,installation kit) are interchangeable between the CVR-80 and CVR-30.

The CVR-30A (P/N 1602-01-03, 1602-02-03) was designed to be in conformance with ARINCSpecification 557 and TSO C123. Therefore, any aircraft which is wired for the CVR-80 willwork properly if the correct (DC vs AC operation) CVR-30A P/N is used and the CockpitControl Unit is exchanged for a TSO C123 unit (P/N 1612-0X, 1613-0X, 1614-0X or RemoteMic Amp P/N 1617-12 with external switch/annunciators). All other accessories areinterchangeable between the CVR-80 and CVR-30A.

The CVR-30B (P/N 1603-02-03) and CVR-120 (1603-02-12) were both designed to be inconformance with ARINC Specification 757 and TSO C123a. Therefore, any aircraft which iswired for the CVR-80, CVR-30 or CVR-30A will work properly with the addition of a strap tothe CVR 30B or CVR-120 and when the Cockpit Control Unit is exchanged for a TSO C123aunit (P/N 1634-0X, 1632-0X, 1633-0X or Remote Mic Amp P/N 1637-XX with externalswitch/annunciators and Area Microphone 16301-0X or 16101). All other accessories are

interchangeable between the CVR-80 and the CV-30B or CVR-120.When the CVR-80 is converted to a CVR-30 or CVR-30A, all internal components are replacedwith new components and the resulting CVR is a zero time unit. The CVR-80, CVR-30 andCVR-30A cannot be converted to a CVR-30B or CVR-120. These units must be exchanged.The CVR-30B can be converted to a CVR-120 with no notable differences other than recordingtime.

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Service Letter No. 2724 Page 2 of 2Rev. C 23 May 2002

The following list summarizes the differences between the units.

a. The CVR-30, CVR-30A, CVR-30B and CVR-120 use solid state memory to retain data,whereas the CVR-80 uses tape.

b. The CVR-30, CVR-30A and CVR-30B record 30 minutes of data. The CVR-120 records120 minutes of data. The CVR-80 records 80 minutes.

c. The CVR-30, CVR-30A, CVR-30B and CVR-120 Installation Manuals specify a 1A circuitbreaker for +28 VDC operation, whereas the CVR-80 Manual specifies a 3A circuitbreaker. The 3A circuit breaker is acceptable for the CVR-30, CVR-30A, CVR-30B andCVR-120 since the input wiring (20 AWG) is the same in all installations.

d. The CVR-30 P/N 1601-01-3 (for DC operation only) weighs 20.5 lbs.

The CVR-30 P/N 1601-02-3 (DC or AC operation) weighs 21.0 lbs.

The CVR-30A P/N 1602-01-03 (for DC operation only) weighs 23.0 lbs.

The CVR-30A P/N 1602-02-03 (for DC or AC operation) weighs 23.7 lbs.

The CVR-30B P/N 1603-02-03 (for DC or AC operation) weighs 13.0 lbs.

The CVR-120 P/N 1603-02-12 (for DC or AC operation) weights 13.0 lbs.

The CVR-80 P/N 1600-0X (DC or AC operation) weighs 20.2 lbs.

e. Installation Manuals and Test and Checkout procedures for the CVRs are different, andeach CVR model requires its designated test set to interface via the front connector. Aterminal or PC is also required for the CVR-30, CVR-30A, CVR-30B or CVR-120checkout procedure.

f. The CVR-80 requires shock mounts for helicopter installations, whereas the CVR-30,CVR-30A, CVR-30B and CVR-120 do not.

g. The CVR-30, CVR-30A, CVR-30B and CVR-120 have two additional pins designated

Rotor Speed Input for helicopter installations. The CVR-80 does not use these pins.

i. The CVR-30A requires a TSO C123 Cockpit Control Unit P/N 1612-0X, 1613-0X, 1614-0X, or Remote Mic Amp P/N 1617-12 with external switch/annunciators.

j. The CVR 30B and CVR-120 require a TSO C123a Cockpit Control Unit P/N 1634-0X,1632-0X, 1633-0X or Remote Mic Amp P/N 1637-XX, 1635-02 with externalswitch/annunciators and Remote Area Microphone 16301-0X or 16101).

k. A strap (record on) must be added between Pins 7 and 8 of P1 for CVR-30B and CVR-120installations.

l. The CVR-30, CVR-30A and CVR-80 require ARINC Rack Key Code 01, whereas theCVR-30B and CVR-120 require the ARINC Rack keying be changed from Key Code 01 toKey Code 22.