AMC 25.1459 Flight data recorders

ED Decision 2020/024/R

1.       General

The installation of a recorder with an ETSO authorisation against ETSO-C124c (or equivalent standard accepted by EASA) satisfies the approval requirement in CS 25.1459(a).

In showing compliance with CS 25.1459, the applicant should take into account EUROCAE Document No ED-112A ‘MOPS for Crash Protected Airborne Recorder Systems’ or a later revision.

‘FDR system’ designates the flight data recorder (FDR) and its dedicated equipment. It may include the following items as appropriate to the aircraft:

a.       The equipment necessary to:

i.        acquire and process analogue and digital sensor signals;

ii.       store the recorded data in a crash-survivable recording medium; and

iii.      when necessary, support dedicated sensors.

b.       Digital data busses and/or networks providing communications between elements of the system.

‘Deployable recorder’ designates a flight recorder that is installed on the aeroplane, and which is capable of automatically deploying from the aeroplane.

2.       Automatic means to stop the recording after a crash impact

Refer to the Section of AMC 25.1457 titled ‘Automatic means to stop the recording after a crash impact’.

3.       Means for pre-flight checking of the recorder

The means for pre-flight checking of the recorder should be able to detect and indicate the following:

a.       a loss of electrical power to the flight recorder system;

b.       a failure of the data acquisition and processing stages;

c.       a failure of the recording medium and/or drive mechanism; and

d.       a failure of the recorder to store the data in the recording medium as shown by checks of the recorded data including, as far as is reasonably practicable for the storage medium concerned, its correct correspondence with the input data.

4.       Recorder container

Refer to the Section of AMC 25.1457 titled ‘Recorder container’.

5.       Combination recorder

Refer to the Section of AMC 25.1457 titled ‘Combination recorder’.

6.       Deployable recorder

Refer to the Section of AMC 25.1457 titled ‘Deployable recorder’

7.       Instructions for Continued Airworthiness (ICA)

When developing the ICA for the FDR system, required by CS 25.1529 and Appendix H, the applicant should address all the failures that may affect the correct functioning of the FDR system or the quality of the recorded data.

Examples of failures (indicative and non-exhaustive list):

—          Loss of the recording function or of the acquisition function of the FDR;

—          Any parameter (required by CS 25.1459(a)(1) or by the applicable air operations regulations) is missing, or is not correctly recorded;

—          Failure of a sensor dedicated to the FDR system;

—          Failure of a means to facilitate the finding of the FDR recording medium after an accident (e.g. an underwater locating device or an emergency locator transmitter attached to the recorder);

—          Failure of the start-and-stop function;

—          Failure of a means to detect a crash impact (for the purpose of stopping the recording after a crash impact, or for the purpose of deploying the recorder if it is deployable).

In addition, the ICA should include the following items, unless the applicant shows that this is not applicable:

—          Calibration checks of parameters from sensors dedicated to the flight data recorder to verify the accuracy of these parameters; and

—          FDR decoding documentation.

i.        Definitions

FDR decoding documentation: a document that presents the information necessary to retrieve the raw binary data of an FDR data file and convert it into engineering units and textual interpretations.

Fixed-frame recording format: a recording format organised in frames and subframes of a fixed length and that are recorded chronologically. ARINC Specifications 573 and 717 provide an example of a fixed-frame recording format.

Variable-frame recording format: a recording format based on recording frames which are individually identified and time stamped, so that their order in the recording file is not important. ARINC Specification 767 provides an example of a variable-frame recording format.

ii.       Content of the FDR decoding documentation

The FDR decoding documentation should at least contain information on:

—         the aircraft make and model;

—         the date and time when the document was modified; and

—         in the case of a fixed-frame recording format:

—         the sync pattern sequence;

—         the number of bits per word, of words per subframe, and of subframes per frame; and

—         the time duration of a subframe;

—         In the case of a variable-frame recording format, the list of frames, and for each frame:

—         its identification;

—         information on whether the frame is scheduled or event-triggered;

—         the recording rate (for a scheduled frame);

—         the frame event condition (for an event-triggered frame); and

—         the list of parameters, by order of recording;

—         For every parameter:

—         its identification: name (and mnemonic code or other identification if applicable);

—         the sign convention and the units of converted values (if applicable);

—         the location of each component of a parameter in the data frame;

—         instructions and equations to assemble the components of each parameter and convert the raw binary values into engineering units (if applicable); and

—         the conversion to text or the discrete decipher logic (if applicable).

iii.      Format of the FDR decoding documentation

The FDR decoding documentation should:

—         be provided in an electronic format;

—         contain all the information described in paragraph f.ii. above; and

—         comply with the standard of ARINC Specification 647A or a later equivalent industry standard.

[Amdt 25/23]

[Amdt 25/26]