ronewart – Page 3 – Blue Box Driver

High on glue !

We started replacing worn-out fabric on our C-3 with Ceconite. Rick (right) is a jack of all trades and has been helping with Blue Box refurbishment for years. After ripping off the old fabric, sanding the wood and priming it with poly, we asked Leroy (left) if he would be our tutor. Leroy is an airplane fabric expert. He recovered Wright Patterson AFB Training SPO’s Blue Box many years ago; and he recovered the Memphis Belle’s ailerons with authentic cotton for the Air Force Museum. Leroy is trying to teach us tricks of the fabric trade.

“Do you smell something?”

We were working on our C-3. We finally got the directional gyro working; after 3 disassembles / reassembles. All of our fuselage instruments were working except for the clock, for the first time. Then Rick said “Do you smell something?” Things went from best-ever to bad in an instant. Smoke billowed out of the control box as we fumbled for the OFF switch. Wax from the burning autosyn transformer dripped into a pool inside the control box. We opened the building doors to let the smoke outside.

Doesn’t quite fit

#6-40 screw used in the wind drift calculator.

With trainers approaching 80 years old, it’s no wonder many substitutions have been made over the years. Here’s one we have seen several times. Original Blue Box trainers frequently used #6-40 screws; the most common #6 machine screw today is a #6-32. When a #6 machine screw just doesn’t fit right – it may be the wrong thread.

A similar problem occurs with small set screws; Blue Boxes often use Bristol or spline. When standard Allen wrenches don’t fit, get out a magnifying glass and see if a Bristol is in order.

Connector tags

Air Speed “AS” stamped metal tag in remote instrument box.

The remote instrument box includes three primary Telegon instruments, each with identical 5-pin AN connectors. To avoid confusion, Link labeled them with small stamped metal tags. “AS” air speed, “VS” vertical speed, and “ALT” altimeter. Those little labels withstood the test of time.

Stressed Out

Original #8581 bracket (right). Lateral crack near bottom goes all the way across bracket.

Sometimes parts are worn out or broken beyond repair. The original part #8581 (right) is a lever and bracket assembly that supports a pivot point for linkages going back to the tachometer regulator. Like several brackets in the fuselage, it is cast from pot metal. This bracket had many cracks and was broken in several places due to fatigue. We made the substitute (left) from aluminum. Ours doesn’t look as cool but is functional.