Aluminum Overcast

[B-25 C]

Aluminum Overcast was at the Bessemer, AL. Airport on the 6th & 7th. this month. Last time she was here was 2002 at the Birmingham, AL. Airport. She is in good shape. She now has the squat switch on the mains. It was good to hear her again.

[warbird1]

Aluminum Overcast was at the Bessemer, AL. Airport on the 6th & 7th. this month. Last time she was here was 2002 at the Birmingham, AL. Airport. She is in good shape. She now has the squat switch on the mains. It was good to hear her again.

Did she previously NOT have a squat switch on the mains? I'm not familiar with B-17s' squat switches. I would have assumed that most had them in order to give a gear indication in the cockpit. Is this not correct?

Does this somehow relate to the inadvertent gear up fiasco at Burbank several years ago?

[ZRX61]

Does this somehow relate to the inadvertent gear up fiasco at Burbank several years ago?

Van Nuys

[cott]

Not sure how much a squat switch would have helped in Van Nuys. The problem was that the landing gear wasn't fully extended prior to touchdown. The mains didn't retract on landing. The jackscrews broke because the wheels were only about 75% of the way down.

[warbird1]

So, do most B-17's have squat switches or not? If not, how does one tell if the gear is down or not? Is there some kind of landing gear pole or indicator out on the wing?

[Rod Schneider]

I'm not sure about the others, but Liberty Belle has squat switches and position switches. The squat switches are open when the struts are compressed (weight on wheels) and they disable the retraction circuit. The position switches are located on the retract/extend screw jack. The retract position switch shuts off the retract motor at the end of travel. The extend position switch shuts of the motor at full extend and turns on the green light for that gear. My understanding of the Aluminum Overcast accident was that the gear did not fully extend, which puts the screw jack under considerable load when the plane touches down.

[Chris]

The B-17 should also have red stripes that line up when the gear is fully extended. My question now is, WHY did they land knowing that the gear was not fully extended. Were their position swithches not functioning? Did they not have the emergency crank to manually lower the gear on board? My understanding was that after touchdown, the call was made to raise the flaps and the pilot not flying hit the gear switch instead because it was not a guarded switch. Without squatch switches, there would have been nothing to open the circuit when the strut was compressed thus causing the jack screws to raise the gear to the point where the link between the jack screw and the main strut failed. The plane rolled quite a ways after touchdown before the gear collapsed. Seems it would have failed on touchdown with all the force generated by the landing. This was the scenario told to me by someone at Van Nuys. Hope I'm wrong. But it does seem funny that squatch switches were installed AFTER the incident.

[Ethan]

That makes more sense

[cott]

On the Overcast, the landing gear switch isn't quite like on most regular airplanes. You don't throw the switch and the gear extends to the stops. It is a three position switch that has to be put back into neutral when the extension or retraction is complete. The Van Nuys accident was pilot error in that they put the switch back into neutral prior to full extension. They neglected to look out the window to visually check the gear prior to touchdown. Actually, the airplane landed just fine with the gear partially extended. The gear collapsed when the pilots hit the brakes to turn off the runway.

[pmahaffey]

B-17's do normally have squat switches as standard equipment on each main gear. If either squat switch is closed it will disable the entire retraction system. We test them every time we do a gear retract test on the ground.
As a note of interest there is also a centering switch on the tail wheel retract circuit. If the shear bolt fails (which can happen if too much side load is put on the tail wheel on the ground with the tailwheel locked) the tailwheel will not be lined up with the wheel well and major damage can result if it is retracted that way. The switch opens the circut to the motor on the tailweel to prevent it from retracting.

Patrick Mahaffey
B-17 "Chuckie"
B-25 "Pacific Prowler"

[Holedigger]

The more I read about B-17's the more I realize I don't know SQUUAT! It is a shame when such a little error does so much damage, guess that's why there are checklists, dull, monotonous, and so basic....and yet, without them, BAD things happen. Like the airliner over the FL swamp at night, a burned out bulb caused the crash, they forgot to FLY the plane!

[Chris]

Not sure I totally agree with you Cott. While the gear switch does have a neutral position, if you move it to the gear down position, the gear will extend until they strike the limit switch which will open the circuit. If the limit switches are functioning properly, there is no need to return the gear switch to the neutral position until well after landing usually on the after landing checklist. We will lower the gear on the pilots call and visually check all three alignment marks and will use the checklist to verify. The switch will stay in that position for the remainder of the flight. In either the neutral or gear down position, there should be a spring tab on the gear switch which prevents the gear switch from being moved to the up position without physically lifting the spring tab. Right after the Overcast incident, we modified our checklist so that the pilot not flying cannot raise the FLAPS without the Flight mechanic or other pilot visually verifying that he is on the correct switch. As soon as Sentimental Journey gets back, I'll take some pics of the switch.