Is there a third "black box" beside the FDR and CVR?

[TREXBORLON]

The officials in Iran say they've found two out of the three black boxes of the Caspian Airlines Tu-154M that crashed last week.
I'm wondering what the third black box is if it actually exist on any aircraft.

[Cough]

Tu154 may be different to the western metal that we are familiar with.

But on most modern stuff, they would look for CVR, FDR and QAR. QAR is not crash proof but does tend to store much more data.

[singpilot]

There were 3 boxes on the Tupolev. All have been found. All of them had broken open, and the tapes were exposed to crash forces and spilled liquids. Investigators were saying they thought that the tapes could be salvaged and read.

[lomapaseo]

Singpilot

Could you elaborate on what each of the three black boxes capture for data?

[bcgallacher]

Coughs reply is probably correct - A Quick Access Recorder is a maintenance aid and is not hardened like the others.

[muduckace]

The QAR is also often used to transmit parameters to ACARS, it is a amall unit. A Digital Flight Data Aquisition Unit is more common, it is used in conjunction with the DFDR or FDR.