Required functions and present coverage
| Function | Why it matters | Present coverage | Next action |
|---|---|---|---|
| Magnetic heading | Part-NCO instrument function | Compass plus probable heading indicator | Confirm compass condition and stabilised-heading serviceability. |
| Barometric altitude, IAS and VSI | Basic instrument flight | Conventional instruments visible | Verify pitot/static condition, tests and pitot heat. |
| Turn/slip, attitude and stabilised heading | Instrument control and failure safeguards | Conventional six-pack visible | Confirm power source, warnings and serviceability. |
| OAT, accurate time and power warnings | Required/supporting indications | Not fully established | Identify and test. |
| Suitable communication | ATS and airspace requirements | TY91 plus COM upgrade work | Document final 8.33 configuration. |
| Suitable surveillance | Airspace requirement | TT31 Mode S | Confirm configuration and altitude source. |
| Conventional VOR/DME/ILS | Route/approach capability and training | Promising, unusually comprehensive | Prove exact glideslope/indicator installation and serviceability. |
| Approved GNSS/PBN | Modern routes and RNP procedures | Not identified | Install approved navigator and guidance display if justified. |
| Navigation failure outcome | Required planning/resilience principle | Potentially strong if conventional equipment remains serviceable | Document practical contingency for intended routes and approaches. |
Focused proposed addition
Garmin GPS 175
An installed SBAS GNSS navigator supporting en-route PBN and database-driven GNSS procedures, including LNAV, LP and LPV where those minima are published and available. It contains no COM, VOR, localiser, glideslope or DME receiver.
Approved course display
A GI 275 Base/CDI can display lateral and vertical GPS guidance in an approved compatible installation. It is not an ADAHRS attitude instrument and cannot replace the artificial horizon. If an existing approved indicator can be used legally and coherently, a new display may not be necessary.
The installation scope includes antenna, harnesses, circuit protection, source selection/annunciation as required, panel work, configuration, tests, weight-and-balance amendment, approved installation data, AFM supplement, PBN documentation and current navigation databases.
Priority order
| Priority | Work | Reason |
|---|---|---|
| 1 | Resolve fuel-indication and any other airworthiness defects | Dispatch baseline precedes optional capability. |
| 2 | Complete and document COM work | Establish reliable 8.33 kHz communication. |
| 3 | Inspect/test instruments, NAV, DME, ADF, indicators and pitot heat | Avoid replacing useful equipment based on assumptions. |
| 4 | Establish AFM/supplement and modification-record basis | Confirms what operations and installations are approved. |
| 5 | Add approved GNSS/PBN and suitable course guidance | Fills the main modern navigation gap. |
| 6 | Improve real-IMC failure resilience if needed | Consider battery-backed attitude and electrical endurance. |
| 7 | Modernise engine indication if independently justified | Useful for engine management, but not an IFR-navigation enabler. |
Shopping-list decisions
| Item | Assessment |
|---|---|
| GPS 175 | High-value addition after baseline defects and checks. |
| GI 275 Base | Useful only if needed as the approved GPS guidance display; not an attitude replacement. |
| GI 275 EIS and sensor kit | Defer unless it is selected as an approved remedy for poor/failed engine indications or wanted for engine management. |
| PAI-700 vertical-card compass and mount | Optional while the existing magnetic compass is serviceable and satisfactory. |
| Bad Elf Flex Mini | Remove from plan; duplicates Aero Tracker's GNSS feed and adds no approved IFR function. |
Practical end state
The preferred result is a coherent set of independent functions: serviceable conventional attitude and air-data instruments, retained VOR/localiser/DME capability, approved GNSS guidance, reliable 8.33 COM, Mode S surveillance, sensible electrical resilience and a clearly separate SkyDemon/Aero Tracker awareness layer.