Appendix 3 FIGURE 3-5. PART 121 FLIGHT RECORDER PARAMETER REQUIREMENTS § 121.344a Manufactured Before 8/18/1997?
§121.344a(b)(1) Appdx M 57 parameters 3 .
B.3 Listed in §121.344a(f)?
YES §121.344a(c) Appdx M 88 parameters.
YES Not required to comply with part 121.
May be required to comply with §135.152.
END NO Manufactured After 8/19/2002?
Manufactured After 8/18/2000?
YES Brought on US Register after 10/11/1991?
Foreign Registered and added to US Ops Spec after 10/11/ 1991?
NO NO Not required to carry a FDR.
§121.344a(1)(2)(3) 181 or 222 parameters listed in §121.344(a). Ranges, YES D YES From Page A3-3 §121.344 10-19 Passenger Seats?
Less than 10 seats?
YES YES NO YES NO NO END Not required to carry a FDR NO Page A3-8 §135.152
accuracies, and resolutions as specified in part 135 Appndx B.
1 Either parameter listed below must be recorded:
§121.344(a)(12) or (a)(15) §121.344(a)(13) or (a)(16) §121.344(a)(14) or (a)(17) For airplanes with more than two engines, §121.344(a)(18) must also be recorded if sufficient capacity is available on the existing recorder.
Parameters §§121.344(a)(12) through 121.344(a)(17) each may be recorded from a single source.
2 Commensurate with the capacity of the recording system (FDAU or equivalent and the DFDR).
3 Commensurate with the capacity of the recording system, all additional parameters (88) listed in §121.344(a) for which information sources are installed and which are connected to the recording system.
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AC 20-141B 06/23/23 Appendix 3 FIGURE 3-6. PART 125 FLIGHT RECORDER PARAMETER REQUIREMENTS § 125.226 Manufactured on or before 10/11/91?
Flight Data Acquisition Unit (FDAU) as of 07/16/1996?
Airplane listed in §125.226(l)(2)?
YES YES YES No FDAU More than two engines?
§125.226(b) Appdx D. Record 17 parameters.
Parameter 18 req’d based on capacity.
§125.226(b) Appdx D. Record 18 parameters YES NO Analog FDAU §125.226(b) Appdx E. Record 22 parameters.
Parameter 12-17, single source allowed.
§125.226(c) Appdx E. Record 22 parameters 1 .
Parameters 12-14, single source allowed.
Digital FDAU NO Manufactured after 8/19/2002?
§125.226(f) Appdx E 88 parameters 2 Manufactured after 8/18/2000?
NO YES §125.226(e) Appdx E 57 parameters 1,2 §125.226(d) Appdx E 34 parameters 1 NO Manufactured before 8/18/1997?
NO YES C.1 Page A3-7 §125.225 C END From Page A3-1 Transport category and turbine powered?3 YES NO Not required to carry an FDR.
END NO 1 Commensurate with capacity, any other parameters (of 88) that have source installed and connected to recording system.
2 For Boeing 737 airplanes manufactured after August 18, 2000, parameters 88 through 91 are required to be recorded by February 2, 2011.
3 Aircraft originally certificated under Aero Bulletin 7A are not transport category aircraft.
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From Page A3-6 §125.226 YES §125.225(a) Appdx D 11 parameters .
YES NO NO NO §125.225(f) Appdx D 17 parameters .
NO END ">----"""""" ____ ,.. Not required to carry an YES YES END FDR §125.225 Appdx D All parameters in Appdx D that are available on bus.
§125.225 Appdx D 29 mandatory and 12 recommended parameters 8/17/10 AC 20-141B Appendix 3 FIGURE 3-7. PART 125 FLIGHT RECORDER PARAMETER REQUIREMENTS § 125.225 A3-7
Appendix 3 FIGURE 3-8. PART 135 FLIGHT RECORDER PARAMETER REQUIREMENTS § 135.152 Listed in §135.152(k) and manufactured YES Not required to carry an END before FDR 8/18/1997?
From Page A3-1, Page A3-2 $91.609, Page A3-3 $121.343, or NO Page A3-5 $121.344a 10-30 seat airplane YES Manufactured YES $135.152(), manufactured after after 8/19/2002? 88 parameters Appdx F 8/18/2000?
NO §135.152(i), Appdx F NO 57 parameters Non-US 10-19 YES onto US Brought NO registered, NO passenger added to US Op seats? register after 10/11/1991? Specs after 10/11/1991?
§135.152(a), Appdx YES B (airplane) 18 parameters YES NO or C (rotorcraft) 23 parameters Airplane with 20-30 or YES Manufactured _ NO Type NO rotorcraft with 20 or certificated after after 10/11/1991?
more passenger 9/30/1969?
seats?
YES YES NO §135.152(b)(3), Appdx D (airplane) 29 + 17 {135.152(b)(2), 22 §135.152(b)(1), 11 optional parameters parameters per Appdx parameters per Appdx B (airplane) B (airplane) or or or E (rotorcraft) 25 parameters C (rotorcraft) C (rotorcraft) A3-8
Appendix 4 APPENDIX 4. TYPICAL REASONABLENESS AND QUALITY CHECK
INSTRUCTIONS
1. General. The operator must accomplish a reasonableness and quality check of the recorded flight data to ascertain that the data is being recorded correctly and that noise and data dropouts do not interfere with the ability to interpret the recorded data. The check may be performed using data that is in electronic format or hardcopy. If a hardcopy printout is used, data traces should also be available. The check must be performed using data that has been extracted in EU because octal, BCD, or hexadecimal coded data do not provide the analyst a clear understanding of how the parameters are varying and how they are correlated to each other.
2. Checklist. The analyst must use a checklist to confirm that all necessary checks have been accomplished. The checklist must refer the analyst to troubleshooting or repair procedures if a suspect parameter is identified.
3. Flight segment selection. The data to be used by the analyst should be extracted from both the takeoff and the landing phases of flight. During the cruise segment of a flight the parameters remain steady, and therefore movement of related parameters cannot be correlated. The takeoff and landing segments of flight provide the analyst an opportunity to observe data that is changing as the aircraft climbs, descends, accelerates, decelerates, and banks or turns.
Furthermore, many parameters not exercised during the cruise segment are exercised during the takeoff and landing segments. We recommend the analyst conduct the review of parameters over several flight segments.
4. Sign conventions. Each aircraft has a pre-established sign convention for the direction of movement of its flight control surfaces. It is imperative the analyst be able to confirm proper direction of movement and not just verify movement. Therefore, the sign convention should be included in the checklist or the analyst should review the assigned sign conventions before beginning the check.
5. Failed parameters. The analyst should examine the extracted data to determine if parameters normally vary in flight, e.g., flight controls, flight control surface positions, and heading, are indeed varying. Values at their “maximum limit” or unvarying indicate an inoperative sensor or other failure. Accelerometers tend to fail at the “maximum limit” position.
If the accelerometer trace is not moving during all segments of the flight check, check to see if it indicates maximum or minimum acceleration. An accelerometer failure indicating a mid-point value is uncommon.
6. Correlation to other parameters. The reasonableness check should include a check of the correlation between parameters that depend upon each other. For example, if roll increases, a turn is indicated and heading should begin to change soon after the increase is detected. Also, aileron position and control wheel position should have changed immediately before the roll initiates. There may even be a variation in lateral acceleration. Again, it is important the analyst confirm movement is indicated in the proper direction according to the aircraft sign convention.
Table 4-1 is provided as an aid to prepare a reasonableness checklist. It summarizes parameters in a 34-parameter DFDRS that may be expected to interact. A check mark () in a block indicates the parameter identified in the row and the parameter identified in the column are A4-1
Appendix 4 interdependent at some time during takeoff and climb or approach and landing. Therefore, the movement of one parameter should cause or be caused by movement in the other. The following examples show how to use Table 4-1 in developing a reasonableness checklist for each parameter.
a. Thrust reverser position reasonableness and quality check. In Table 4-1, the column labeled Thrust Reverser Positions (number 22) contains check marks in the rows labeled Airspeed, Engine Thrust, Longitudinal Acceleration, Autopilot AFCS Mode, and Air/Ground Sensing. The normal expectation is for the thrust reverser to deploy during rollout after landing.
Thus, the following checklist might be developed using the parameters identified by a check mark.
(1) Examine the thrust reverser in-transit data and the thrust reverser deployed data to determine they indicate in-transit only for a short period during the landing roll and deployed at the end of the in-transit period. The data should indicate in-transit and the deployed discrete should indicate stowed near the end of the landing roll.
(2) Examine the engine thrust data during the in-transit period and immediately after the deployed indication. During the in-transit period, engine thrust should have decreased to near zero. Immediately after the thrust reverser deployed indication, the engine thrust should have increased to near the maximum indication.
(3) Examine the airspeed and longitudinal thrust data. These two parameters should be decreasing during the in-transit period and should dramatically decrease immediately after the deployed indication.
(4) Examine the autopilot mode discrete and the air/ground sensing discrete. The autopilot mode discrete should indicate the autopilot has disengaged and the air/ground sensing switch discrete should indicate that the aircraft is on the ground.
(5) Examine the remaining data for the thrust reverser discretes to ascertain that no in-transit or deployed indications appear. If intermittent indications appear, determine they are within allowable values and do not have sufficient duration to be interpreted as an actual deployment.
b. Lateral control surface position reasonableness and quality check. The column labeled Lateral Control Surface Positions contains check marks in the rows labeled Heading, Roll Attitude, Lateral Control Position, and Localizer Deviation. The lateral control surfaces are typically ailerons used in establishing the aircraft in a turn and returning the aircraft to straight flight from a turn. The lateral control surface position data may be checked along with the lateral control position data. These checks may be accomplished during the approach and landing segment.
(1) Examine the lateral control surface position trace for deviations during the initial approach segment. A large deviation would normally indicate the aircraft turning onto final approach heading. Check the lateral control position and roll attitude make a large change at the same time.
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1. Time
2. Pressure altitude ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
3. Airsoeed ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
4. Headina ✓ ✓ ✓ ✓
5. Vertical acceleration ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
6. Pitch altitude ✓ ✓ ✓ ✓ ✓ ✓
7. Roll.altitude ✓ ✓ ✓ ✓ ✓
8. Man1Jal microohone keuina ✓ ✓
9. Enoine thrust ✓ ✓ ✓ ✓ ✓
10. Autooilot enaaaement ✓ ✓
11. lonoitudinal acceleration ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
12. Pitch control oositions ✓ ✓ ✓ ✓ ✓ ✓
13. Late-ral control oositions ✓ ✓ ✓ ✓
14. Yaw control oositions ✓ ✓ ✓
15. Pitch control surface oositions ✓ ✓ ✓ ✓ ✓ ✓
16. late-ral control surface oositions ✓ ✓ ✓ ✓
17. Yaw control surface oositions ✓ ✓ ✓
18. late-ral acceleration ✓ ✓ ✓
19. Pitch trim surface oositions ✓ ✓ ✓ ✓ ✓ ✓
20. Trailina edae flaos ✓ ✓ ✓ ✓ ✓
21. leadino edoe flaoslslats ✓ ✓ ✓ ✓ ✓
22. Th11Jst reverser oositions ✓ ✓ ✓ ✓ ✓
23. Ground sooiler oosition ✓ ✓ ✓
24. OAT/TAT ✓
25. Autooilot, AFCS modes ✓ ✓ ✓
26. Radio altimeter ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
27. localizer deviation ✓ ✓ ✓ ✓ ✓ ✓
28. Glideslooe deviation ✓ ✓ ✓ ✓ ✓ ✓
29. Marker beacon ✓ ✓
30. Master warnino
31. Airlaround sensina ✓ ✓ ✓ ✓ ✓ ✓ ✓ -
32. Anole of attack ✓ ✓ ✓
33. H11d1aulic oressure low I
34. Ground Soeed ✓ ✓ ✓ ✓ ✓ ✓ ' 8/17/10 AC 20-141B Appendix 4
(2) Check to determine heading begins to change immediately after the lateral control surface position begins to change. Heading should continue to change after the lateral control surface position returns to the zero or null value. The heading data should begin to change at a lower rate when the lateral control surface position data moves in the opposite direction. When the lateral control position is returned to zero or null, the heading data should again be constant.
(3) Check the localizer deviation for changes. Small lateral control surface position and lateral control position data changes should accompany deviations from the localizer and returns to the localizer course null.
(4) Check the lateral control surface position data to determine there are no data dropouts and there is no noise in the data. If dropouts or noise are detected, determine they are within allowable values and they would not be interpreted as an actual control surface position movement.
TABLE 4-1. PARAMETER CORRELATION A4-3
Appendix 5 APPENDIX 5. CONSIDERATIONS FOR FILTERED FLIGHT DATA
1. Purpose of this appendix. This appendix addresses the recording of filtered flight data and means of compliance with the “Filtered Flight Data” final rule published on February 19, 2010 (75 FR 7345) and effective as of April 20, 2010. The following guidance expands on terms, discusses the scope, and provides information for operators on how to comply with this rule.
2. Discussion of terms used in the regulations.
a. What is an original sensor signal?
(1) An original sensor signal is the direct electronic output from:
(a) A sensor, or
(b) A system that accepts multiple sensor inputs.
(2) An air data inertial reference unit (ADIRU), an inertial reference system (IRS), and an ADC are examples of systems capable of producing an original sensor signal. For example, an ADC accepts multiple sensor inputs from pitot-static tubes and temperature probes. These inputs are processed by the ADC to output information, such as airspeed, outside air temperature, and pressure altitude. In this case, we consider the original sensor signal node to be at the output of the ADC.
b. What is parameter accuracy? In 14 CFR part 121 appendix M (and appendix E in part 125 and appendix F in part 135), the third column heading label reads “Accuracy (sensor input).”
The parenthetical “sensor input” refers to the signal recorded by the DFDR that is provided by a sensor, or system as described in paragraph 2.a(1) of this appendix. The total parameter accuracy is a function of the DFDR recorded value when compared to the actual measured value at the same point in time. For example, parameter accuracy is the difference between an actual physical measurement of a flight control surface and the corresponding DFDR recorded value.
Accuracy is typically expressed as a tolerance in EU or a percentage.
c. What is dynamic condition?
(1) The term “dynamic condition” was introduced in the regulations in 1997 and is found in 14 CFR part 121 appendix M, Airplane Flight Recorder Specifications, (and appendix E in part 125 and appendix F in part 135). Until April 20, 2010 the introductory text to appendix M previously stated:
“The recorded values must meet the designated range, resolution, and accuracy requirements during dynamic and static conditions. All data recorded must be correlated in time to within one second.”
A5-1
Appendix 5
(2) Prior to the filtered flight data final rule publication on February 19, 2010, there was no clarification for the meaning of dynamic condition. Our expansion of dynamic condition was adopted from NTSB safety recommendations A-03-048 through 050. The introductory text to appendix M now states:
“The recorded values must meet the designated range, resolution, and accuracy requirements during dynamic and static conditions. Dynamic condition means the parameter is experiencing change at the maximum rate attainable, including the maximum rate of reversal. All data recorded must be correlated in time to within one second.”
(3) For example, under dynamic conditions, the maximum attainable rate of control surface movement is dependent on the flight control system design of the aircraft. When performing certification testing under dynamic conditions (see definition in appendix 6), the maximum rate attainable includes rates encountered in both normal and abnormal operating conditions. When performing continued airworthiness testing (see functional check definition in appendix 6), it is not necessary to demonstrate the maximum rate attainable under dynamic conditions.
d. What is filtered data? As defined by 14 CFR §§ 121.346(a), 125.228(a), and
135.156(a), flight data is filtered when an original sensor signal has been changed in any way, other than changes necessary to:
(1) Accomplish analog to digital conversion of the signal,
(2) Format a digital signal to be DFDR compatible, or
(3) Eliminate a high frequency component of a signal that is outside the operational bandwidth of the sensor.
Note: Removing noise and aliased signals are industry standard techniques included under paragraph 2.d(3).
e. What is reconstructed data? Reconstructed data is derived from recorded filtered values by applying a unique algorithm to the filtered values. The final rule allows an option to reconstruct filtered data if the recorded DFDR values do not comply with the accuracy requirements in 14 CFR part 121 appendix M (or comparable appendices in parts 125 and 135).
A certificate holder must submit the procedure and the test results that demonstrate an original sensor signal value can be reconstructed from the recorded data.
3. Scope.
a. What parameters are allowed to be filtered? All parameters are allowed to be filtered.
The final rule distinguishes between the following two groups of parameters:
(1) Group 1 – Parameters (1) through (11), (18) through (41), (43) through (87), and (89) through (91). These parameters are allowed to be filtered with no further action.
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Appendix 5
(2) Group 2 – Parameters (12) through (17), (42), and (88). If these parameters are filtered, then the operator has two options. These options are discussed in paragraph 3.c(2) below.
b. How to identify if a Group 2 parameter is filtered?
(1) An operator should check its DFDR system engineering and maintenance documentation to determine those parameters that are considered by definition to be filtered.
Wiring diagrams may be necessary to trace the electronic signal from its origin to the DFDAU.
(2) If an operator does not possess the necessary information to determine if a Group 2 parameter is filtered, then the operator may choose to consult the TC, STC, or ATC holder to obtain the necessary information for its aircraft.
c. What are the options if a Group 2 parameter is identified as being filtered?
(1) After a parameter in Group 2 is identified as being filtered, the operating certificate holder must confirm that the accuracy of the parameter is in compliance with 14 CFR part 121 appendix M in both static and dynamic conditions, as specified in the appendix introductory text.
Note: Parameter 42 (power/throttle lever position) is required to be sampled one time per second. The certificate holder may show by quantitative analysis that the filtered data does not affect the parameter’s accuracy.
(2) If the operating certificate holder identifies a filtered parameter not in compliance with the accuracy requirements, the operator has two options. An operator must either redesign the DFDR system to record the original sensor signal, or demonstrate to the FAA that the filtered data can be reconstructed to be in compliance with 14 CFR part 121 appendix M (or comparable appendices in parts 125 and 135). However, if the FAA determines that the reconstruction procedures are not acceptable, then the operator must have the DFDR system redesigned.
4. Compliance times and documentation.
a. What is the compliance schedule?
(1) Operators have 18 months, no later than October 20, 2011 (reporting date), to inspect their DFDR systems and document their findings whether or not their DFDR systems record filtered data for any of the parameters included in Group 2. The operator must create a record of this determination for each airplane on its operations specifications. The operator must maintain this record as part of the correlation documentation required by 14 CFR §§ 121.344(j)(3),
125.226(j)(3), or 135.152(f)(2)(iii). If any of those recorded signals are being filtered, then the operator must identify which parameters are affected. If the parameters are not being filtered, then the operator must document its finding and is not required to take further action, unless a future change is made to its DFDR system.
(2) Operators that report filtered parameters will have two options.
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Appendix 5
(a) If an operator chooses to remove the filtering, it has to make the modifications no later than April 21, 2014 (thirty months from the last permissible reporting date).
(b) If an operator chooses to demonstrate by test and analysis that filtered data can be reconstructed, the operator has to submit its reconstruction package, including the procedures and test and analysis results, in the correlation documentation to its FAA certificate holding district office for approval no later than April 22, 2013 (18 months from the reporting date). The final year is needed for the FAA to review the documentation and verify the procedure and test results are repeatable.
(3) In all cases, compliance with the rule is required by April 21, 2014 (four years from the effective date). In no case will the submission of reconstruction procedures and test and analysis results be considered compliance until that submission is approved by the FAA.
Operators who choose that method of compliance are cautioned to submit their procedures and test and analysis results as early as possible in case their submissions fail to be approved and other action is needed.
b. May an operator submit data from the airframe manufacturer? Yes, operators may submit documentation from airframe manufacturers to comply with 14 CFR §§ 121.346(d)(1),
125.226(d)(1), or 135.156(d)(1). However, for all airplanes of a particular model, the operator must record the individual airplane serial number and U.S. registration number in the correlation documentation for all airplanes on its operations specifications that have identical DFDR systems.
c. How does the operator show compliance? By the last permissible reporting date (October 20, 2011), all operators must have updated correlation documentation stating which of the listed parameters in 14 CFR § 121.346(c) is filtered or not filtered by definition. This must be done for each aircraft listed in the operator’s operations specifications. There are three cases in which an operator would show compliance:
(1) At the report date, no later than October 20, 2011, the operator updates its correlation documentation to show its DFDR system does not record any filtered data for the parameters listed in 14 CFR § 121.346(c). For all airplanes of a particular model, the operator must record the individual airplane serial number and U.S. registration number in the correlation documentation for all airplanes on its operations specifications that have identical DFDR systems.
(2) An operator identifies a Group 2 parameter as being filtered in its correlation documentation and opts to reconstruct the original sensor signal values. The operator must submit the procedures and test and analysis results to reconstruct the filtered data as early as possible, no later than April 22, 2013. The data package must be the updated correlation documentation with at least the following information:
(a) Operating certificate holder name, aircraft type, and DFDR system description, A5-4
Appendix 5
(b) Name, number, and accuracy of the parameter as defined by the applicable operating rule,
(c) Actual measured data from the original source signal exercised in static and dynamic conditions,
(d) Raw DFDR data of the filtered parameter exercised in static and dynamic conditions,
(e) EU conversion algorithm,
(f) Filtered data reconstruction algorithm, and
(g) Analysis of the reconstruction algorithm applied to the raw DFDR data.
(3) An operator identifies a Group 2 parameter as being filtered and opts to redesign the DFDR system to record original sensor signal data. This case is handled through the STC process.
5. Flowchart. Figure 5-1 is a flowchart of the filtered flight data final rule. This flowchart breaks down the regulatory requirements in 14 CFR § 121.346. Figure 5-1 can be applied to the similar requirements in 14 CFR §§ 125.228 and 135.156.
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