Overhaul Period; Special Inspection Requirements; Application Of Protective Treatments; Data Relative To Structural Fasteners - Garmin GI 275 Maintenance Manual

3.6 Overhaul Period

The system does not require overhaul at a specific time period. Power on self-test and continuous BIT will
monitor the health of the GI 275 system. If any LRU indicates an internal failure, the unit may be removed
and replaced. Refer to Section 4 of this document for fault corrective actions.

3.7 Special Inspection Requirements

After a suspected lightning strike, the following actions must be performed for the specified LRU:
GTP 59 OAT Probe
Inspect the GTP 59 for signs of lightning damage. Check the self-sealing washer (P/N 212-00026-00) used
on the probe tip outside of the aircraft for any evidence of melting or lack of seal. Replace the washer if
damaged. If there is evidence of lightning strike to the OAT or any lightning damage, replace the GTP 59
OAT Probe.
Tube-and-fabric aircraft must replace the OAT probe bond strap (if installed) in accordance with Section 4
of the GI 275 installation manuals (refer to Table 1-1).
GMU 11/44B
Aircraft with a GMU mounted in the wingtip of metallic aircraft with non-metallic wingtip covers must
inspect the magnetometer installation for the following conditions:
1. Check the GMU magnetometer body and mount for scorching, soot, melting, pitting, denting, or
discoloration.
2. Check the GMU connectors for melting or pin damage.
3. Check the cable overbraid for pinching, melting, or evidence of arcing.
4. Check the lug for evidence of arcing and verify that the lug is still secured to the overbraid.
5. Check electrical bonding between the GMU overbraid and adjacent aircraft structure. Resistance
should be less than 5 mΩ.
6. If any of these checks shows evidence of a lightning strike, replace the overbraid assembly and
affected components in accordance with Section 4 of GI 275 Part 23 AML STC Installation
Manual.
Perform the Magnetic Interference Check in accordance with Section 6 of GI 275 Part 23 AML STC
Installation Manual. The purpose of this check is to ensure the structure around the GMU did not get
magnetized by the lightning event to the point of affecting magnetometer performance.

3.8 Application of Protective Treatments

None.

3.9 Data Relative to Structural Fasteners

Data relative to structural fasteners, such as type, torque, and installation requirements can be found in
Section 5 of this manual.
3.10

Additional Instructions

None.
190-02246-11
Rev. 1
GI 275 Part 23 AML STC Maintenance Manual
Page 3-7