Buying used avionics for a Cessna 172 can feel exciting and stressful at the same time. New panels look great, but the price can stop many owners fast. Used gear feels like a smart path, but only if you know what works and what causes trouble.
This topic matters because one good choice can save money, while one bad choice can ground your airplane. Let’s slow it down and walk through what really counts when shopping for used avionics.
Key Takeaways
Used avionics for a Cessna 172 can be safe to buy if they are certified, tested, and in good working order, but some older or unsupported units should be avoided. Good used avionics can save money and still give clear navigation, radios, and GPS, but very old systems may be hard to repair or may not work with today’s airspace rules. The safest choices are well-known brands with logbook history and shop testing, while risky choices are outdated units with no support, missing paperwork, or unknown condition.
| Avionics Type | Safe to Buy If | Avoid If | Why It Matters |
| GPS units | IFR-approved and tested | No WAAS or no support | Needed for legal and safe navigation |
| Radios (COM/NAV) | Clear audio, recent check | Static, weak signal | Communication is critical |
| Transponders | ADS-B Out compliant | Not ADS-B capable | Required in most airspace |
| Glass displays | From trusted brand, serviced | Very old or discontinued | Repairs may be impossible |
| Autopilots | Fully working, shop inspected | Parts no longer made | Failures affect safety |
| Unknown units | Full logbook history | No records or testing | Hidden problems cost more later |
What “Used Avionics” Really Means for a Cessna 172
When people say used avionics, they usually mean equipment removed from another airplane and sold again. This can include screens, boxes, and radios that once lived in another panel. For a cessna 172, this is common because the fleet is large and parts move around often.
Used does not mean broken. Many units come from planes that got a panel upgrade or were parted out after an overhaul. Some owners remove working gear to install newer setups. That gear then becomes a source for used equipment.
Here is what counts as used in real life:
- A radio pulled from a flying airplane
- A transponder removed during an ads-b install
- A nav unit replaced by newer gear
- A screen swapped out for a different layout
Avionics live in the cockpit, and that space matters. Older panels were built around a steam gauge layout. Many older cessna 172 panels still use a round gauge setup. Used avionics often fit these spaces better than brand-new, wide screens.
Some units were made for 172s and fit easily. Others need panel work. That adds cost. Always think about fit before buying.
Used avionics also come with paperwork. This includes tags, logs, and approval paths like an stc. Without these, your mechanic or a&p may not be able to sign it off.
Popular used items you may see include:
- audio panel units
- Older GPS units with waas
- Simple engine monitor displays
- Analog replacements for the vacuum system
Pilots flying in general aviation value gear that works every day. Many 172 pilots share real experiences on places like pilot's place forums. These stories help explain what lasts and what causes headaches.
The key idea is simple. Used avionics are real aircraft parts, not gadgets. They must match the airframe, the power system, and how the plane is flown.
Why Buying Used Avionics Can Be Smart or Risky
Buying used avionics can save a lot of money. That is the good side. The risk shows up when support, age, or install costs get ignored. For many aircraft buyers, this is where plans go wrong.
The smart side first. Used gear can:
- Lower the entry cost for avionics upgrades
- Keep a used cessna 172 flying without huge bills
- Help when buying a used airplane with outdated gear
- Improve safety in busy airspace
Examples help. A used gnc255 or sl30 can still handle basic nav and comm needs. A used engine analyzers display can protect your engine. These tools do their job well when installed right.
Now the risky side. Problems happen when:
- The unit has no factory support, like some older garmin models
- Parts are no longer made
- Software updates are locked out
- Install costs exceed the purchase price
Big systems raise the stakes. A used autopilot can look like a deal but cost more to install than expected. Large screens like g3x or a gtn650 need wiring, antennas, and setup time. That time costs money at the avionics shop.
Some planes bring special concerns. Buying an older airframe can uncover wiring issues. These are particular gotchas with this airframe that shops see often. Corrosion, old connectors, and poor grounding can slow any install.
Glass upgrades get a lot of attention. Systems like g1000 integrated avionics changed how later models fly. A full g1000 swap is rarely practical. Lighter steps like g5, g5s, or dual g5s work better for many owners. These give solid altitude and attitude data without tearing apart the panel.
Think long term too. When you sell the plane, buyers look at support and reliability. Unsupported gear can hurt resale. Well-chosen used gear can help it.
Finally, match gear to your mission. Flying ifr needs dependable nav and backup systems. A waas gps matters here. Weekend flying may not.
Many owners read aviation consumer reviews and browse trade-a-plane listings to compare setups. A used aircraft guide can also help set expectations.
One last note. A cessna 172 skyhawk with a 180-hp engine may fly faster, but avionics choices still matter. Even a c172 with later models benefits from thoughtful planning. The goal is simple, safe modern avionics that fit how you fly.
How To Check If Used Avionics Will Work in Your 172
Before you buy anything, slow down and check fit, function, and future support. This step protects your wallet and your schedule. Used parts can work great, but only when they match your plane and your flying needs. Let’s walk through the checks in a clear order, one piece at a time.
Start With Your Airplane’s Basics
Every check begins with the airframe and paperwork. Not all 172s are the same. Year, model, and panel layout matter.
Do this first:
- Confirm the exact model and year of your 172
- Review logbooks for past changes
- Note panel layout and open spaces
Some 172’s still use older wiring and systems. Others have already had updates. This affects what will fit and how hard the install will be.
A quick look inside the cockpit helps too. Count open slots. Measure space. Note old wiring bundles. This tells you what is realistic before you shop.
Match the Equipment to the Mission
Next, think about how you fly. This step avoids buying gear you cannot use fully.
Ask simple questions:
- Do you fly ifr or only VFR?
- Do you need a basic radio or full GPS nav?
- Do you fly near busy airspace?
If you plan to fly in weather, you may need GPS with waas approval. If you fly locally on clear days, simpler gear may be fine.
Many buyers get excited and buy avionics like big screens or complex boxes. Pause here. Match tools to real use. This saves money and time.
Check Approval and Paperwork
Approval is not optional. The unit must be legal for your airplane.
Here is what to confirm:
- STC or approval path for your model
- Installation manual availability
- Continued support from the maker
Some units were removed during a panel upgrade or engine overhaul. That does not make them bad. It does mean you need the right paperwork to reinstall them.
If paperwork is missing, installation may stop. That can leave your airplane grounded.
Talk to a Mechanic Early
This step saves the most stress. Before buying, talk to your mechanic or avionics shop.
Bring them:
- The make and model of the unit
- Photos of your panel
- Your flying goals
They can tell you if the install is simple or complex. They can also flag wiring issues or power limits early.
This is where you learn hidden costs. A cheap box can turn expensive if wiring must be replaced.
Look at System Compatibility
Avionics work as systems, not single boxes. Each part must talk to the others.
Check compatibility with:
- Existing audio panel
- Current GPS or nav source
- Transponder and ads-b equipment
If one part cannot talk to another, features may not work. An autopilot may not follow GPS guidance. A display may not show traffic.
This step is vital in mixed panels with old and new gear.
Understand Display and Control Limits
Some pilots prefer round dials. Others like screens. Used gear comes in both styles.
Older panels often center on a gauge layout. Many owners keep this setup and add small screens for key data.
Large systems like g1000 setups are rare to retrofit fully. Smaller steps usually work better and cost less.
Know what the unit shows:
- Navigation data
- Engine data
- Alerts and warnings
Make sure it shows what you need without clutter.
Check Power and Cooling Needs
Avionics need stable power and airflow. Older panels may struggle here.
Confirm:
- Electrical load limits
- Circuit breaker capacity
- Cooling airflow behind the panel
If power is limited, adding one box may mean removing another. This affects planning and cost.
Think About Support and Updates
Support matters long after install day. Some brands still update software. Others do not.
Well-known brands like garmin often have better long-term support. That matters for bug fixes and compliance.
Ask:
- Are updates still available?
- Are repair parts still made?
- Do shops still train on this unit?
Lack of support can limit features and affect safety over time.
Consider Long-Term Value
Think ahead. One day, you may sell.
Buyers look at panels closely. Clean installs and supported gear help resale. Unsupported or confusing setups can slow a sale.
Good used avionics can add value when chosen carefully. Poor choices can do the opposite.
Final Pre-Buy Checklist
Before you pay, run through this list:
- Fits your model and year
- Approved installation path
- Matches your flying needs
- Supported by shops
- Total cost understood
If all boxes check out, you are in a good spot.
Used avionics can work very well in a 172. The key is patience and planning. Think in systems, not parts. Ask questions early. Bring your shop into the process.
A little homework now keeps flying fun later. And yes, it also keeps surprises off the invoice.
Conclusion
Used avionics for a Cessna 172 can be a smart path when choices are slow, informed, and realistic. Focus on support, fit, and total cost, not just the price tag. The right setup keeps flying fun and stress low. If you want help comparing options or planning your next step, visit Flying411 for tools and guidance made for aircraft owners.
Frequently Asked Questions
Are used avionics safe to fly with?
Yes. Used avionics are safe when tested, approved, and installed by a certified shop with proper paperwork.
Can I install any used avionics in my Cessna 172?
No. The equipment must be approved for the aircraft and installed under the right authorization.
Do used avionics save money long term?
They can, but only if support and install costs stay reasonable.
Should I buy used avionics before or after purchase?
Many owners wait until after purchase to match gear to real needs.
Where do most owners find used avionics?
Common places include shops, owner forums, and aircraft marketplaces with verified listings.