Bits and Pieces: A New Panel for Grumman Cheetah C-GQIG

By Ken Potter, EAA 529880, Treasurer, EAA Chapter 245, Carp, Ontario

In the winter of 2017, I began to look around for a hangar for my Nieuport 17 replica which I’d had at home repairing after a forced landing. As we know, like many airports, hangars for sale at Carp Airport in Ottawa are “as rare as hen’s teeth”, and those that do sell are often not advertised. Such was the case with EAA Chapter 245 member Rod Neufeld’s row hangar at EAA 245. I approached Rod’s family about buying the hangar and they replied that I’d have to buy Grumman Cheetah C-GQIG along with the hangar. Hmm, I took a look at the re-sale values for Cheetahs and was encouraged, thinking I could sell the aircraft pretty easily.

Enter chapter member Mark Briggs, EAA 795537, who had been maintaining the airplane for Rod, and flying with him in in recent years. Shortly before the deal was to close Mark said, “Let’s go for a flight.” I wasn’t five minutes into that first flight when I made up my mind that I was not selling the Cheetah. It was a gem to fly and had the performance to allow my bride and me to actually go places farther away than the usual $100 hamburger day trip. So, postponing any exotic vacation for the next two or three years, I dipped into our savings and bought the hangar and Cheetah.

Grumman Cheetah C-GQIG landing at CYRP

Throughout 2017 and 2018 we enjoyed the airplane and put about 130 hours on it with few problems. Of course, this airplane had been maintained by Mark, so it was mechanically sound, however the panel was legacy 1977 including the avionics (it still had an ADF for cripes sakes). Of course, Mark was always there in the background with advice about the airplane and soon talk turned to the unreliability of aircraft vacuum systems and options out there to replace them. Of course, the Garmin G5 was the new kid on the block at that time, and I resolved to go ahead and purchase and install a pair. I suffered from sticker shock when I realized that a pair of certified Garmin G5s were nearly twice the price as the experimental version (and exactly the same instrument). But that was the price of owning a certified aircraft.

The discussion continued and soon came around to how I was going to supply the G5s with navigational data. The aircraft had no GPS and, after some searching, I soon found a new-to-me Garmin GNS 530 WT in California. The seller was very gracious and even had Garmin update the software and maps for me at no charge. 

But the price on what was supposed to be a simple panel improvement had now doubled. 

You see a theme here, don’t you? 

There was no looking back as Mark continued to whisper suggestions for further improvements ($$$$$) into my ear.

Through the winter of 2018-19 I took to removing the instruments from the panel and removing wiring. What a mess some of it was. When an airplane is 43 years old, there have been inevitable modifications and I probably took out a of pound of “ghost” wiring that didn’t lead anywhere. In addition, there were two speakers under glare shield each weighting in at 1.5 lb. But what surprised me most was that the quality of some of the Grumman factory’s electrical work back in 1977 would not have passed an amateur-built aircraft inspection in 2021!

By now the project was expanding into a full panel replacement. Around the time of SUN ‘n FUN 2019 Mark told me about a great deal on a JPI EDM 830 engine monitor on sale. Sure enough, a dealer in Las Vegas of all places had a SUN ‘n FUN sale going on: US $2,000 for the entire system. I purchased it and had it brought back to Canada for me by a “snowbird” chapter member coming back north. Note to file, buying and installing the EDM 830 was some of the best money Mark spent for me on this project, and the monitor would prove invaluable when flight testing began. More on that later.  

Soon the remaining panel details started coming together with the purchase of a PS Engineering 8000 audio panel, a Garmin SL 30 Nav/Com and a Garmin GTX 327 transponder. While not cutting-edge technology, it was looking to be a vast improvement on the old Cheetah panel. Of course, installing Garmin G5s also meant that I had to keep the legacy airspeed indicator, altimeter, and vertical speed “steam gauges,” but the upside was that the vacuum system was gone. Yay!

Earlier in the winter of 2018-19 I had set out to build a new wiring harness, teaching myself along the way. I didn’t get very far in when I realized that this was the one part of the project that had a learning curve I couldn’t keep up with. I began to look around for a company to build a harness for me. One company I inquired with wanted US $4,000 just to draw the harness out for me and, just as I was sinking into the depths of depression thinking the harness would bankrupt me, I stumbled upon a company by the name of Approach Fast Stack. If you’ve not heard of them, they build complete system harnesses based on a hub system. All instrument wiring goes to a central hub where the inter-instrument connections are done.

Sweet, I thought! A quick call to them and they quoted me on the entire harness including hub for US $2,100. I promptly ordered the harnesses and they arrived within two weeks. The company’s support throughout the project was incredible and even after one-and-a-half years when I finally installed the encoder and discovered they had supplied the wrong cable, they graciously sent me a new one at no cost. In the end, all wiring behind the panel was replaced with the exception of the main power wire to the main bus, which was in good shape. 

New connectors and harness

When I started the project, I was semi-retired and thought it would take six months max. Well, the best laid plans as the saying goes. In June 2019 I was offered a chance of a lifetime to become “un-retired” and take up a position with the Transportation Safety Board. This position was supposed to be part-time, but I spent the next six months working full-time and as a consequence the Cheetah panel project slowed down to a crawl.

But work did continue. After 10 months of working hunched over in the cockpit, I began to question if there was a better way if the windshield was removed. Sure enough, inquiring with some online Grumman forums I learned that the windshield came out easily with the removal of 11 bolts. So, one warm late winter day in 2020, Chapter 245 Vice President Mike Lamb, 464057, and I took to removing the windshield; which turned out to be an “easy-peasy” 20-minute job. From then on, I could stand beside the airplane and work behind the panel. My productivity soared and my Robaxacet purchases plummeted.

Windshield removed (yes, that’s my Nieuport 17 tucked in behind the Cheetah)
Back of panel now accessible after windshield removal

One setback happened that vexed me for a couple of months during the winter of 2019-20. The JPI oil temperature probe was supposed to be installed on the upper front of the engine after removing a plug from one of the oil galleries. Well, back in 1977 when the engine was built, Lycoming had never thought that this plug would have to be removed and installed it with some type of glue that made the plug impervious to turning. Firstly, I managed to strip the hex in the plug. Awe thought Ken,”I’ve seen this before”, I’ll just drill it out and use an easy-out. Folks, that plug was made of some sort of super material as it took a diamond tip drill bit to drill a hole. Game on I thought, insert easy-out and start turning until— SNAP! The easy-out broke in the hole.. Luckily no one else was around the hangar or the chapter that afternoon as I turned the air blue with expletives. Folks around the chapter were great though and came up with some ingenious solutions for removing the broken easy-out (although I think they were secretly snickering at my plight). None worked, so I put on my thinking hat and concluded that I couldn’t have been the first idiot to make such stupid move. Turns out I was right; a quick search revealed that the Brown Aviation Tool company in the U.S. made an “easy-out removal tool” which is essentially a diamond studded glorified dentist’s drill. It worked like a charm and I soon had the easy-out and plug removed, the sensor installed, and a whole heap of weight and worry off my shoulders. 

In late February 2020 I ordered a new panel overlay from a supplier in the U.S. to be shipped to the UPS store just across the border in Ogdensburg, New York. My bride and I then went on a 10-day Caribbean cruise. When we arrived home COVID was just starting to spread and shutdowns loomed. I immediately booted it for Ogdensburg to pick up the panel and headed back across the border to Canada. I “dodged a bullet” that time as when I got home, I learned that the border had closed just after my whirlwind trip. With the panel overlay installed, I could start to see light at the end of the tunnel and begin installing instruments.

At Mark’s suggestion I proceeded to change out all of the legacy fuses with Klixon circuit breakers and new bus bars. As well, it was suggested that I change out the 40-year-old switches for new ones. Sigh, another order off to Fletchair, the Grumman parts gurus in Texas but, at less than $5.00 per switch, a good investment.

New breakers to replace original fuses

We were heading into the home stretch now. In an effort to further reduce the aircraft weight I installed a light weight Skytech starter and a B&C 60-amp alternator. Around this time folks started pestering me with the question “when will you be finished?” My stock answer became “Thursday.”

First avionics installed, the Garmin 327 transponder
Panel coming together in summer 2021
Testing all the new avionics.

Fast forward through a myriad of details and this past summer things came together nicely. A new pitot-static system using Steinair’s push to connect fittings and colour-coded tubing was fabricated and installed (so easy to install and visually pleasing). I installed test ports for pitot and static under the glare shield making test connections simple. The system was tested and re-certified by a local Gatineau AME who also calibrated the legacy airspeed indicator and altimeter, and replaced the battery in and re-certified the Kanad 406 ELT.

One of the final changes I made to QIG was to the nose bowl. To remove the nose bowl on a Grumman Cheetah to access the alternator, one has to remove the prop first. When I purchased the aircraft, it came with an STC to split the nose bowl, effectively making it removable with the propeller still in place. In the peak of the summer heat, I worked in the air-conditioned comfort of my living room to do the modifications.

Splitting the nose bowl
Cheetah QIG back together and awaiting flight

Fast forward to this past October and the airplane was together, and ready for a weight and balance check, it’s first since being manufactured in 1977. On a rainy and cool day, I rolled the Cheetah into the chapter hangar and Mark joined me to weigh the old girl using the Chapter’s newly calibrated and certified scales. All went well but we were surprised that, despite all of the weight we had removed, an almost equal amount had been added so the empty weight came out close to the 44-year calculated value. I was not too concerned though as the Cheetah still had an almost 800-pound useful load. While we had not lost weight as expected, we gained much improved reliability and functionality.

Weighing the plane at EAA 245

Next came paperwork, paperwork, and more paperwork in getting ready for the final inspections and sign-offs, which went smoothly. We had run up the engine back in August with the result that I had a couple of small oil leaks and a rough idle. Downloading the JPI EDM 830 engine monitor data showed a fouled plug which was quickly sorted out (yes, the fidelity of the EDM 830 is such that you can detect individual spark plug issues). More engine tests, and a full static run-up followed and the JPI monitor download showed everything was good. The oil leaks went away on their own.

With the annual inspection signed off in November, we were ready to fly. Chapter member and flight instructor extraordinaire Mike Lamb agreed to accompany me as safety pilot and to do an insurance-required rust remover on yours truly. The plan for the first flight was to climb to circuit altitude and then climb out of the downwind to orbit the airfield at 2,300 feet for testing. After that, Mike would put me through my paces to knock the rust off my flying skills followed by testing the new avionics in depth. At the beginning of December 2021, the weather gods finally cooperated and we briefed for the flight. Takeoff was normal but turning crosswind we noticed that the No. 3 cylinder EGT was climbing. Just as I turned downwind and pulled the power back to cruise, the JPI EGT alarm for cylinder No. 3 went off so we cut the flight short, stayed in the circuit and landed.

Analysis of the JPI monitor data showed everything normal at run-up but No. 3 and to a lesser extent No. 4 EGT’s high on climb out. First suspect was possible induction tube air leaks causing a lean fuel mixture. Removal of the induction tubes revealed deteriorated hoses and gaskets which we promptly replaced. 

Full engine ground run-ups showed that the exhaust temperatures were now behaving so, at the end of the first week of Jan uary2022 we took to the air again. After orbiting Carp Airport for half an hour to verify that the engine was behaving, we headed out to the practice area to start that important rust removal and to continue evaluating the new panel operation.

Overall, despite the time it took to replace the panel and instruments, the Cheetah has been brought into the 21st century with a “hybrid” panel at a reasonable cost. I’ve joked over the past two years about chapter member and AME Mark  spending my money for me but I could not have done this project without his encouragement, sage advice, and his polite demeanour when something I did was not up to expectations. Upon spotting a transgression of some sort he would just calmly say, “You know if I was doing that…”

For everyone else, thanks for your support and encouragement.  Thursday has arrived.

The finished article

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