New Tire and Vacuum Pump
On Friday, I met an airplane and powerplant mechanic (A&P) friend at the airport to take care of a few maintenance items. I want to be able to do a some of the maintenance on the plane myself, but as an owner, I’m limited to doing “preventative maintenance” tasks (as described in FAR Part 43). For everything else I need to hire an A&P to do it or to supervise me.
There were three things I wanted to take care of sooner rather than later:
- Replace the vacuum pump - At the end of the last post, I mentioned that the vacuum system had finally given in. When flying visually (VFR) it’s a pain to navigate without a vacuum system, and it’s absolutely required for instrument flying. The Bonanza actually uses a pressure pump to pumps air from outside through the instruments (rather than a traditional vacuum pump that draws air through them and dumps it overboard). Vacuum pumps typically have a designed shearpoint in the shaft that prevents a seized pump from putting back pressure on the engine. When we took the bad pump off the shaft came off in two pieces (see pictures).
- Replace the nose wheel tire - The nose wheel tire was flagged on the prebuy inspection. It was showing cracks and wasn’t holding pressure adequately. It may not have been critical, but it was a chance for me to ease my way into maintenance tasks and knock something simple off the list.
- Replace the missing Wing Bolt Cover - A few weeks ago, my partner was flying the plane and heard a clanking sound just before takeoff. When he landed, he noticed that right hand, upper, forward wing bolt cover was missing. I tracked one down, but haven’t put it on the plane yet. The replacement cover is unpainted, and I’d like to look into getting it painted or wing walk grip applied before I put it on.
The tire and tube came from Desser. I stopped by Honeycutt Aviation (short drive from my house) to get new wheel hardware. The vacuum pump came from Aircraft Spruce. And I picked up the used wing bolt cover from Kevin O’Halloran on BeechTalk.
As expected the vacuum pump swap is pretty straightforward. You need loosen two hose clamps (for air-in and air-out) and four nuts on the engine accessory case bolts, slide the old pump off and the new pump on, put all the hardware back and you’re good to go. The biggest challenge was sliding the nuts and washers off and back on the bolts inside the cramped engine compartment. We did have to go fishing in the bottom cowling for dropped hardware more than once.
Since we were changing the nose wheel tire (not the mains) we didn’t need to use a jack. I pulled the tail of the aircraft down until the nose wheel was a few inches off the pavement. While I was hanging on the tail, my A&P secured it using a ratcheting load strap, attaching one end to the tie down bolt in the pavement of our shade hangar spot and the other end to the tail tie down eye on the airplane.
We had expected to get a small bag of tire talc from Desser with the tube and tire order. When I opened the plastic wrap on the tire package, there was no talc so I made a quick trip to Walgreens for some baby powder. We took the wheel off the axel, split the wheel halves, and walked it all over to one of the shops on the field to have them grease the bearings and break the bead for us. All that was left was to put the new tube in the new tire, put the wheel halves back together, torque the new through bolts, then put it all back on the axel, secure the axel nut with a new cotter pin, and fill the tire to spec. As a side note, the Bonanza Pilot Proficiency Program (BPPP) has a great video on the topic of owner performed maintenance (changing a tire is one of the “preventative maintenance” tasks that a pilot owner can do themselves) that walks through the process of changing a tire in detail.
We wrapped with a single lap in the pattern to confirm we were getting adequate vacuum pressure, and there were no problems with the nose wheel.