Aircraft Inspection Mandatory

Number:
052/08/2011
Date:

Issue:
2

Subject:

Inspection and Maintenance of Transponder Systems

Applicability:

All Sailplanes and Powered Sailplanes with mode A, C and mode S Transponder systems installed

Accomplishment: At installation and at annual inspection

Reason: Instructions:

To comply with ICAO and Part M maintenance and inspection requirements. Note: these requirements form part of the BGA GMP Maintenance Programme .
Part A) Installation

The installation of transponder systems must be in accordance with approved data for the equipment and aerial (approved modification for the aircraft type including installation instructions from the equipment manufacturer). Aerials must be mounted in an approved location. Each ATC airborne equipment provided must comply with the following: (a) The equipment and its aerials may neither in themselves nor by their mode of operation or by their effect upon the operating characteristics of the sailplane and its equipment constitute a hazard to safe operation. (b) The equipment and its control and monitoring devices must be arranged so as to be easily controllable. Their installation must be such that they are sufficiently ventilated to prevent overheating. The equipment must be EASA type approved and be released with an EASA Form 1 (or equivalent).

1. Carry out an electrical load analysis to ensure the power supply is adequate and meets 30 minute reserve power requirements.
2. If the battery supplying the transponder is more than 12 months old, battery capacity must be confirmed with a battery capacity test. (AMP Leaflet 4-9)
3. Encoding altimeter or altitude encoder calibration test (N/A if new equipment is installed) and carry out static system leak test.
4. Ensure all wiring is checked to ensure clearance from any control system

Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
5. Function test in accordance with Part C) Task 8, including verification that the operation of the transponder is not affected by any other system (CS-22.1301) and that "DATA" light illuminates (if fitted)
6. Amend aircraft weight and balance schedule and equipment list. 7. The aircraft radio station license will require updating to include the new equipment 8. Carry out a maintenance check flight to verify the operation of the transponder.
A transponder check should be combined with a Mode-C encoding altimeter check (if fitted), by making a check call to an airspace radar unit. This should be completed at 2000 ft above, and 20 Nm from, a known radar facility. Record check flight result in log book.
Part B) Maintenance (Annual inspection)
Review aircraft and equipment manufacturers maintenance and inspection recommendations for any additional requirements. Note: the following is the minimum maintenance & inspection requirements for BGA sailplanes and powered sailplanes.
Task 1 - Installation Inspect the transponder installation, aerial and mounting structure including ground plane, for integrity, security and damage.
Task 2 – Controls and wiring Inspect all switches, controls, wiring, fuses, connectors and interfaces for integrity, security, signs of overheating and damage. Ensure all electrical wiring is correctly routed free of any moving part or control system.
Task 3 - Displays Inspect displays and indicators, including LCD & back lights, for correct and full display of all characters, symbols and operation. Carry out test using built in test equipment (BITE) if fitted. Ensure "DATA" light illuminates (if fitted)
Task 4 – Airworthiness Directives and Service Bulletins Review all airworthiness directives, service bulletins and technical notes relating to the installed equipment and action as required.
Part C) Maintenance at 24 months to align with annual inspection
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
Task 5 – Static inputs Carry out calibration test of encoding altimeter or altitude encoder (in situ test is acceptable) ref. EASA SIB 2011-15R1 Note: if the results cannot be read directly from the transponder display and specialist test equipment is required this test must be certified by a BGA Inspector with RE authorisation or CAA Licensed radio engineer (see certification & records) Carry out leak test of static system Note: Calibrated test equipment required
Task 6 – Power supply If the battery supplying the transponder is more than 12 months old, carry out battery capacity test (see AMP Leaflet 4-9)
Task 7 – Bonding Carry out bonding test of equipment and aerial including ground plane Note: Calibrated test equipment required
The following tests require certification by a BGA Inspector with Radio Engineer (RE) authorisation or CAA Licensed Radio Engineer.
Task 8 – Function test Carry out receive and transmit function test in accordance with equipment manufacturers information and tolerances (Component Maintenance Manual) using field test set.
In the absence of manufacturers information use Appendix F to FAR 43 (extract below)
Note: The Mode 'S' checks should confirm that the aircraft assigned Mode 'S' code is correct and that any declared parameters are correct. (See G-INFO for assigned code) Note: Calibrated test equipment required Note: If the equipment manufacturer states in published literature that no maintenance testing is required and provided there is no Airworthiness Directive mandating a test, the function test (task 8) may be omitted if there are no adverse flight reports. Other equipment supplying data to the transponder e.g. altitude encoders or encoding altimeters not covered by the statement are required to be tested as per this instruction. The annual inspection (part B) and bi annual check (part C) as applicable, are required on all transponder installations.
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
Certification and records Record all work on BGA 284 and additional worksheets and aircraft log book in accordance with M.A.401 (c) Use BGA 284 to record routine maintenance and inspections The installation, annual and bi-annual inspections with the exception of Task 5 (if applicable) and Task 8 Transponder function test may be certified by a BGA inspector with GL authorisation. Task 5 (if applicable) and Task 8 can only be certified by a; BGA inspector with Radio Engineer (RE) authorisation, or CAA section L licensed radio/radar licensed engineer with paragraph 12.3 endorsement, or Part 66 B2 licensed engineer holding an aeroplane group and without limitations 6 or 7 issued with a BGA Radio Engineer (RE) authorisation.
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
Appendix F to FAR 43—ATC Transponder Tests and Inspections
The ATC transponder tests required by §91.413 of this chapter may be conducted using a bench check or portable test equipment and must meet the requirements prescribed in paragraphs (a) through (j) of this appendix. If portable test equipment with appropriate coupling to the aircraft antenna system is used, operate the test equipment for ATCRBS transponders at a nominal rate of 235 interrogations per second to avoid possible ATCRBS interference. Operate the test equipment at a nominal rate of 50 Mode S interrogations per second for Mode S. An additional 3 dB loss is allowed to compensate for antenna coupling errors during receiver sensitivity measurements conducted in accordance with paragraph (c)(1) when using portable test equipment.
(a) Radio Reply Frequency:
(1) For all classes of ATCRBS transponders, interrogate the transponder and verify that the reply frequency is 1090 ±3 Megahertz (MHz).
(2) For classes 1B, 2B, and 3B Mode S transponders, interrogate the transponder and verify that the reply frequency is 1090 ±3 MHz.
(3) For classes 1B, 2B, and 3B Mode S transponders that incorporate the optional 1090 ±1 MHz reply frequency, interrogate the transponder and verify that the reply frequency is correct.
(4) For classes 1A, 2A, 3A, and 4 Mode S transponders, interrogate the transponder and verify that the reply frequency is 1090 ±1 MHz.
(b) Suppression:
When Classes 1B and 2B ATCRBS Transponders, or Classes 1B, 2B, and 3B Mode S transponders are interrogated Mode 3/A at an interrogation rate between 230 and 1,000 interrogations per second; or when Classes 1A and 2A ATCRBS Transponders, or Classes 1B, 2A, 3A, and 4 Mode S transponders are interrogated at a rate between 230 and 1,200 Mode 3/A interrogations per second:
(1) Verify that the transponder does not respond to more than 1 percent of ATCRBS interrogations when the amplitude of P2pulse is equal to the P1pulse.
(2) Verify that the transponder replies to at least 90 percent of ATCRBS interrogations when the amplitude of the P2pulse is 9 dB less than the P1pulse. If the test is conducted with a radiated test signal, the interrogation rate shall be 235 ±5 interrogations per second unless a higher rate has been approved for the test equipment used at that location.
(c) Receiver Sensitivity:
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
(1) Verify that for any class of ATCRBS Transponder, the receiver minimum triggering level (MTL) of the system is −73 ±4 dbm, or that for any class of Mode S transponder the receiver MTL for Mode S format (P6 type) interrogations is −74 ±3 dbm by use of a test set either:
(i) Connected to the antenna end of the transmission line;
(ii) Connected to the antenna terminal of the transponder with a correction for transmission line loss; or
(iii) Utilized radiated signal.
(2) Verify that the difference in Mode 3/A and Mode C receiver sensitivity does not exceed 1 db for either any class of ATCRBS transponder or any class of Mode S transponder.
(d) Radio Frequency (RF) Peak Output Power:
(1) Verify that the transponder RF output power is within specifications for the class of transponder. Use the same conditions as described in (c)(1)(i), (ii), and (iii) above.
(i) For Class 1A and 2A ATCRBS transponders, verify that the minimum RF peak output power is at least 21.0 dbw (125 watts).
(ii) For Class 1B and 2B ATCRBS Transponders, verify that the minimum RF peak output power is at least 18.5 dbw (70 watts).
(iii) For Class 1A, 2A, 3A, and 4 and those Class 1B, 2B, and 3B Mode S transponders that include the optional high RF peak output power, verify that the minimum RF peak output power is at least 21.0 dbw (125 watts).
(iv) For Classes 1B, 2B, and 3B Mode S transponders, verify that the minimum RF peak output power is at least 18.5 dbw (70 watts).
(v) For any class of ATCRBS or any class of Mode S transponders, verify that the maximum RF peak output power does not exceed 27.0 dbw (500 watts). Note: The tests in (e) through (j) apply only to Mode S transponders.
(e) Mode S Diversity Transmission Channel Isolation:
For any class of Mode S transponder that incorporates diversity operation, verify that the RF peak output power transmitted from the selected antenna exceeds the power transmitted from the non selected antenna by at least 20 db.
(f) Mode S Address:
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.

BGA 052/08/2011 issue 2
Interrogate the Mode S transponder and verify that it replies only to its assigned address. Use the correct address and at least two incorrect addresses. The interrogations should be made at a nominal rate of 50 interrogations per second.
(g) Mode S Formats:
Interrogate the Mode S transponder with uplink formats (UF) for which it is equipped and verify that the replies are made in the correct format. Use the surveillance formats UF=4 and 5. Verify that the altitude reported in the replies to UF=4 are the same as that reported in a valid ATCRBS Mode C reply. Verify that the identity reported in the replies to UF=5 are the same as that reported in a valid ATCRBS Mode 3/A reply. If the transponder is so equipped, use the communication formats UF=20, 21, and 24.
(h) Mode S All-Call Interrogations:
Interrogate the Mode S transponder with the Mode S-only all-call format UF=11, and the ATCRBS/Mode S all-call formats (1.6 microsecond P4pulse) and verify that the correct address and capability are reported in the replies (downlink format DF=11). (i) ATCRBS-Only All-Call Interrogation:
Interrogate the Mode S transponder with the ATCRBS-only all-call interrogation (0.8 microsecond P4pulse) and verify that no reply is generated.
(j) Squitter:
Verify that the Mode S transponder generates a correct squitter approximately once per second.
(k) Records:
Comply with the provisions of M.A.401 (c) as to content, form, and disposition of the records. [Amdt. 43–26, 52 FR 3390, Feb. 3, 1987; 52 FR 6651, Mar. 4, 1987, as amended by Amdt. 43–31, 54 FR 34330, Aug. 18, 1989]
Approved By Jim Hammerton, Chief Technical Officer
Issued by - The British Gliding Association Ltd, 8 Merus Court, Meridian Business Park, Leicester. LE19 1RJ. Note: Mandatory inspections must be recorded in the aircraft log book, unless specified, and certified by an appropriately rated BGA inspector.
Optional inspections should be entered into the D.I. book or log book as appropriate. Optional inspections may be certified by a BGA Pilot. Alternative methods of compliance will be considered providing an equal level of safety is accomplished. Contact BGA for authorisation.