13.6 Altimeter Jerkiness. Some altimeters may exhibit a tendency toward jerkiness (when not under vibration). If the jerkiness appears excessive, then conduct a friction test as described in part 43 appendix E.
13.7 Encoder Errors. Some encoders may exhibit errors and excessive drift during initial warmup. Lack of correspondence within 125 feet between altimeter and encoder, if observed 5 minutes after initial power turn on or later, should be considered failure to meet the standards of § 91.411(a). Only after the repair of the encoder should subsequent retesting occur.
13.8 Encoder Calibration. Adjustment of encoder calibration, including high or low reference settings, is considered a repair action not part of certification and requires an appropriate instrument or limited rating. Limited ratings authorizing the test of encoders only do not include authorization for this adjustment.
Note: No field adjustments are allowed unless the repair station is rated for this adjustment.
14 INSTALLATION AND TESTING CONCERNS.
14.1 Altitude Encoding Capability. The blind encoder, altimeter, air data system components, and encoding altimeter should have an altitude encoding capability of at least the service ceiling or maximum certificated altitude of the aircraft. If the altitude reporting system will not function throughout the aircraft operational envelope (up to the aircraft maximum operating altitude), install a placard stating the aircraft altitude limitation.
14.2 Installation Location. The altimeter and encoder must be installed in the same environmental location unless the person performing the installation obtains specific FAA engineering approval to deviate from this requirement.
14.3 Shop Test ing and Functional Tests. Altitude reporting system installations (either blind encoder or encoding altimeter types) may be tested in the shop by a technician for correspondence (using the transponder decoded output) and then functionally checked after installation in the aircraft, provided the transponder encoding digitizer, altimeter, wiring harness, and coaxial cable are either installed in the aircraft or accurately compensated for.
14.4 Deterioration and Repairs. Transponder antenna systems may deteriorate to the point that they pull transponder frequency out of tolerance. If this occurs, then the repair station should notify the operator that the antenna system requires repair. The practice of offsetting transponder output frequency to compensate for antenna system pull is not acceptable.
14.5 Purging. Whenever there is reason to suspect that the static lines are blocked, purge them before performing the static pressure system test. Besides the obvious benefits of removing foreign objects from the lines, purging may keep such objects from entering the
14 test equipment. Since purging applies positive pressure to lines, take the following precautions:
1.
Disconnect all instruments and air data sensors;
2. Cap off those lines not being purged;
3. Restrain hoses that can whip due to purge pressure;
4. Ensure that lines are clear by feeling discharge pressure at ports; and
5. Clean system drains and traps after purging, since they can act as a sump for foreign material.
14.6 Quick Disconnect Static Line Ports. When opening quick disconnect static line ports, you should accomplish a visual inspection or static pressure system test.
John S. Duncan Director, Flight Standards Service
Appendix A A-1 APPENDIX A. TA BLES TABLE A-1. ABBREVIATED CORRESPONDENCE TEST ALTITUDE
INFORMATION PULSE POSITION Integrity of code lines is ensured through testing at these increments.
RANGE PULSE POSITION
(0 or I in a pulse position indicates absence or presence of a pulse, respectively)
INCREMENTS (FEET)
D4
A1
A2
A4
B1
B2
B4
C1
C2
C4 -1000 0 0 0 0 0 0 0 0 1 0 -900 0 0 0 0 0 0 0 1 1 0 -700 0 0 0 0 0 0 1 1 0 0 -400 0 0 0 0 0 0 1 0 1 1 -200 0 0 0 0 0 1 1 0 0 1 800 0 0 0 0 1 1 0 0 0 1 2800 0 0 0 1 1 0 0 0 0 1 6800 0 0 1 1 0 0 0 0 0 1 14800 0 1 1 0 0 0 0 0 0 1 30800 1 1 0 0 0 0 0 0 0 1
Appendix A A-2 TABLE A-2. CORRESPONDENCE TEST ALTITUDE INFORMATION
PULSE POSITIONS
RANGE PULSE POSITION (0 or 1 in a pulse position indicates absence or presence of a pulse respectively)
INCREMENTS (FEET)
D4
A1
A2
A4
B1
B2
B4
C1
C2
C4
- 1050 to - 950 0 0 0 0 0 0 0 0 1 0
- 50 to + 50 0 0 0 0 0 1 1 0 1 0 450 to 550 0 0 0 0 0 1 0 0 1 0 950 to 1050 0 0 0 0 1 1 0 0 1 0 1050 to 1150 0 0 0 0 1 1 0 1 1 0 1250 to 1350 0 0 0 0 1 1 1 1 0 0 1450 to 1550 0 0 0 0 1 1 1 0 1 0 1750 to 1850 0 0 0 0 1 0 1 0 0 1 1950 to 2050 0 0 0 0 1 0 1 0 1 0 2550 to 2650 0 0 0 0 1 0 0 0 1 1 2650 to 2750 0 0 0 0 1 0 0 0 0 1 2950 to 3050 0 0 0 1 1 0 0 0 1 0 3950 to 4050 0 0 0 1 1 1 1 0 1 0 5950 to 6050 0 0 0 1 0 0 1 0 1 0 6750 to 6850 0 0 1 1 0 0 0 0 0 1 7950 to 8050 0 0 1 1 0 1 1 0 1 0 9950 to 10050 0 0 1 1 1 0 1 0 1 0 11950 to 12050 0 0 1 0 1 1 1 0 1 0 13950 to 14050 0 0 1 0 0 0 1 0 1 0 14750 to 14850 0 1 1 0 0 0 0 0 0 1 15950 to 16050 0 1 1 0 0 1 1 0 1 0 17950 to 18050 0 1 1 0 1 0 1 0 1 0 19950 to 20050 0 1 1 1 1 1 1 0 1 0 21950 to 22050 0 1 1 1 0 0 1 0 1 0 24950 to 25050 0 1 0 1 1 1 0 0 1 0 29950 to 30050 0 1 0 0 0 0 1 0 1 0 30750 to 30850 1 1 0 0 0 0 0 0 0 1 34950 to 35050 1 1 0 1 1 0 0 0 1 0 39950 to 40050 1 1 1 1 0 1 1 0 1 0 44950 to 45050 1 1 1 0 0 1 0 0 1 0 49950 to 50050 1 0 1 0 1 0 1 0 1 0
Appendix A A-3 TABLE A-3. TEST ASSOCIATION MATRIX The following table lists appropriate tests to assure system functionality after removal, replacement, or installation of altitude reporting equipment and transponder system components.
COMPONENT DESCRIPTOR TESTs Altimeter Pilot reference. 1. Field elevation verification.
2. Correspondence test.
3. Static leak test.
Altimeter Pilot reference.
Matched to encoder prior to installation.
1. Field elevation verification.
2. Abbreviated correspondence test.
3. Static leak test.
Altimeter Other than pilot reference. 1. Field elevation verification.
2. Static leak test.
Encoding altimeter Pilot reference. 1. Field elevation verification.
2. Abbreviated correspondence test.
3. Static leak test.
Encoding altimeter Other than pilot reference. 1. Field elevation verification.
2. Correspondence test.
3. Static leak test.
Encoding altimeter Other than pilot reference.
Matched to pilot reference altimeter prior to installation.
1. Field elevation verification.
2. Abbreviated correspondence test.
3. Static leak test.
Blind altitude encoder Connected to transponder. 1. Correspondence test.
2. Static leak test.
Blind altitude encoder Connected to transponder.
Matched to pilot reference altimeter prior to installation.
1. Abbreviated correspondence test.
2. Static leak test.
Blind altitude encoder Not connected to transponder. 1. Abbreviated correspondence test (modified).
2. Static leak test.
Combined static probe/air data computer Installed as single component without opening static system.
1. Single indicated altitude and transponder pressure altitude correspondence verification.
Transponder High reliability style connector system. 1. Transponder test and inspection.
Transponder Non-high reliability style connector system.
1. Transponder test and inspection.
2. Abbreviated correspondence test.
Appendix B B-1 APPENDIX B. DEFINITIONS
1. Approved. Unless used with reference to another person, means approved by the Administrator.
2. Blind Encoder (Digitizer). An altitude reporting encoder that is pressure operated, having no altitude display; is not part of a pressure/altitude indicating device or system; does not contain an external means for barometric setting; and may supply altitude reporting information to the air traffic control (ATC) transponder, Global Positioning System (GPS), or other onboard system.
3. Calibrated Datum of the Altimeter. The correction applied via a specific calibration card applicable to a specific altimeter to correct for instrument error (scale error) only.
4. Correspondence. The maximum absolute difference between altimeter display and encoder output for a constant encoder output. The altimeter’s displayed pressure/altitude (referenced to
29.92) compared to encoded altitude output from the blind encoder or encoding altimeter for the entire period (from the moment that the code output changes to a value to the moment the code output changes to the next value while the pressure/altitude is changing).
5. Data. Drawings, sketches, stress analyses, reports, operating limitations, or photographs that support or describe an alteration.
6. Encoding Altimeter (Pressure Altitude). An altitude indicator that displays to the pilot the pressure/altitude sensed by the device and produces an altitude reporting output.
7. Gillham Encoder. An altitude reporting encoder that provides parallel data output employing the Gillham (Grey) code.
8. Indicated Datum of the Altimeter. The altitude displayed by the altimeter when an ideal absolute pressure is applied to the sensing member of the altimeter and not corrected for instrument error (scale error), nor corrected for static source error.
9. Matched Components. An altimeter and a blind encoder that have been tested and calibrated together and, as a combination, meet the requirements of 14 CFR part 91, § 91.411(a).
10 High Reliability Style Connectors. Connectors designed to or meeting Military or similar industry standards.
11. Pilot Reference Altimeter. The altimeter normally used to maintain flight altitude.
Appendix C C-1 APPENDIX C. TSO-C112 C MARKING AND PART 43 APPENDIX F CLASS C.1 The Technical Standard Order (TSO)-C112c, Air Traffic Control Radar Beacon System/Mode Select (ATCBS/Mode S) Airborne Equipment, labeling scheme does not match the labeling called out in 14 CFR part 43 appendix F. The new TSO labeling is based on RTCA, Inc. DO- 181D, Minimum Operational Performance Standards for Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment, Section 1.4.6, rather than the labeling that had been defined previously in TSO-C112.
C.2 To assist operators in complying with part 43, the following table shows the relationship between the TSO-C112c (or later version) labeling scheme and the part 43 appendix F requirement. Equipment approved under previous versions of TSO-C112 are not affected and may continue to use the label from the equipment directly. Manufacturers of TSO-C112c equipment are encouraged to include this cross-reference information in their operating guide and maintenance instructions.
TABLE C-1. TSO-C112C MARKING AND PART 43 APPENDIX F CLASS 1Pe ATC Mode S Transponder Equipment Part 43, Appendix F Class Reference TSO-C112c (or later version) Transponder1 marking: 14 CFR Part 432, Appendix F class:
Level 1, Class 1 Class 1A Level 1, Class 2 Class 1B, with optional 1090 + 1 MHz reply frequency Level 2, Class 1 Class 2A Level 2, Class 2 Class 2B, with 1090 + 1 MHz reply optional frequency Level 3, Class 1 Class 3A Level 3, Class 2 Class 3B, with 1090 + 1 MHz reply optional frequency Level 4, Class 1 Class 4 Level 4, Class 2 Class 4, except for RF peak output power suppression, which should apply Class 3B and Level 5, Class 1 Class 4 Level 5, Class 2 Class 4, except for RF peak output power suppression, which should apply Class 3B and r RTCA Inc., DO-181E, S ection 1.4.6—with options noted in Section 1.4.4.
2The part 43 marking shown here originated in the original version of TSO-C112.
Appendix D APPENDIX D. SECTIONS 91.411 AND 91.413 COMPLIANCE FLOWCHART FIGURE D-1. SECTIONS 91.411 AND 91.413 COMPLIANCE FLOWCHART Transponder 24-month § 91.413 (a) test due? Test in accordance appendix F with part 43 Altitude Reporting 24-month Altimeter System and § 91.411(a)(1) test due? Test in accordance paragraph (a)-(c) with part 43 appendix E No No Test in accordance est in accordance Correspondence Test Transponder Data with part 43 Static System Test and with part 43 appendix E Inspection required? appendix E, required? paragraph (c) § 91.411(a)(2) paragraph (a) $ 91.413 (b) § 91.411 test and Altitude Reporting Data est in accordance Instrument flight rules (IFR) aircraft? inspection not required See Note 1 Correspondence Test required? with part 43 appendix E § 91.411(a)(3) paragraph (c) Note 1: Further test and inspection is not required under 14 CFR § 91.411, however the FAA recommends meeting the higher standards Complete, no further test prescribed for IF use. or inspection required D-1
Appendix E E-1 APPENDIX E. STATIC PRESSURE SYSTEM PROOF TEST A proof test may be conducted to demonstrate the integrity of the static pressure system in the following manner:
E.1 Unpressurized Airplanes. Evacuate the static pressure system to a pressure differential of approximately 1inHg or to a reading on the altimeter, 1,000 feet above the aircraft elevation at the time of the test. Without additional pumping for a period of 1 minute, the loss of indicated altitude must not exceed 100 feet on the altimeter.
E.2 Pressurized Airplanes. Evacuate the static pressure system until a pressure differential equivalent to the maximum cabin pressure differential for which the airplane is type certificated is achieved. Without additional pumping for a period of 1 minute, the loss of indicated altitude must not exceed 2 percent of the equivalent altitude of the maximum cabin differential pressure or 100 feet, whichever is greater.
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