Small progress is being made nearly daily right now, some moments it feels like nothing has happened while others are major milestones.
Seeing the goal in sight is both exciting and maddening as there is still work to be done.
The engine compartment of Sis goingback together with the exhaust system being reinstalled, electrical wires being secured, and instrument leads reattached.
Sis is a 1947 Beechcraft Bonanza model 35, one of the first 1000 off the assembly line. For all intents and purposes, she is my big sister as I have grown up flying with her and now am her caretaker.
Having the manuals on the restorers phone and tablet has been a godsend for quick reference.
In this case it was the torque values for the exhaust nuts and what weight oil should be used for the given temperature – 50 weight above 40 degrees and 40 weight below.
If nuts are tightened beyond the torque values indicated for the application, they can become stripped.
As we are still working on getting her put back together, the determination of which weight oil will be made when weather is considered for flight.
Exhaust Stacks
Like everything else that has been off of Sis for a while, the exhaust stacks have been inspected for condition and cleaned before reattaching.
With Sis jacked up, it is easier for the restorer to reach into the lower engine compartment and work. After aligning the holes, it was apparent they would have to be positioned halfway onto the studs before everything would fit.
When reattachment of the exhaust was assured, the stack was removed to place the gaskets for each pipe then realigned and attached.
The threads of the exhaust nuts were coated with a thin layer of anti-seize before attaching. Once all were in place, they were torqued to the appropriate value.
After the exhaust was in place, the probes for the engine monitor could be reattached.
The probes stick into holes within the exhaust stack and have wires going back to the instrument in the panel.
Wiring Reroute
Some areas of the wiring showed evidence of heat exposure, which the restorer said we could correct by moving the location of the wire bundle, attaching in a different manner, and shielding where needed.
Wrapping heat shielding around the bundle took a little bit of time but was well worth the effort. Once completed, it looked like it would handle anything the heat from being next to the exhaust would throw at it.
The heat shielding we used was an orange color and could be wrapped around the wiring in its current position. A white line down the middle of the wrap gave a visual indication of overlap while wrapping the wires.
The restorer attached the wrapped bundle to the lower baffle with Adel clamps to relocate it from its previous location – close to the heat generated from the exhaust stack.
Using Adel clamps to attach the wiring bundle to the intake tubes the restorer said the process could be aggravating to secure but could be more appropriate than zip ties for areas where heat is a concern.
The restorer routed the wiring bundle along the baffle that extends from the back of the engine and drilled several holes to screw clamps holding the bundle into place.
The relative warmth of the days this week has made for more comfortable working conditions at Sis’ hangar.
Thinking in three dimensions while reinstalling pieces has been necessary. The area inside the cowling seems like a lot of room until maneuvering larger pieces like the exhaust stacks into place. After several tries at installing the exhaust pipe on the left side which includes the muffler, the restorer was successful after removing a shroud which was reinstalled after in place.
Looking at the pieces that make up the system, I asked if carbon monoxide could be a problem.
As the outside temperatures are colder, using cabin heat during flight is likely. During summer months, cabin heat is not used and but colder temperatures require heat to offset outside conditions. Cabin heat on Sis is a byproduct of engine exhaust. Ensuring welds are intact is necessary to prevent carbon monoxide entering the cabin. Ducts direct the warm air around the exhaust stack into the cabin through a gate which is controlled by a knob within the cabin.
The ducts on Sis, along with other items, will be replaced over time once relocated to the restorers hangar.
Carbon monoxide poisoning can be fatal. The gas is colorless and odorless, an indicator within the cabin is the only way to show the pilot there is a problem. While not required by the FAA, it is advisable to have a detector on board.
There are numerous types of detectors available. The one I almost convinced dad to get was a dot that changed color when carbon monoxide is present. The biggest advantage this indicator has is its very inexpensive, however it is not entirely reliable.
The restorer and I discussed several other options and decided on a unit with an audible alarm and a display which can be mounted inside the cabin.
We both appreciate the piece of mind that this unit will provide especially during colder weather.
After getting the exhaust system into place, it was obvious another piece was missing. This time, a heat deflector that attaches to the exhaust. The bracket is still in place, but the piece is not there. Another joy of antique and vintage ownership!
The restorer has reached out to some sources for parts, with one providing pictures of a part removed from another aircraft in poor condition.
If necessary the part will be fabricated.
Weighing what must be done and what can be deferred is necessary in so many areas of life, not just getting Sis back into the air.
The time we are spending to ensure she flies again safely reminds me once again to slow down and take things one step at a time.
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