B-17 suffers gear collapse on landing roll

More insight into the gear collapse from the EAA website

B-17 UPDATE: VIDEO HELPING OFFICIALS UNDERSTAND INCIDENT

May 12, 2004 – As analysis of the landing incident that damaged EAA’s B-17 Aluminum Overcast continues at Van Nuys Airport in California, EAA officials are beginning to get a clearer picture as to exactly what occurred after the airplane touched down safely on Wednesday, May 5. EAA reported earlier this week that recently obtained video footage shows the entire incident from approach to touchdown, rollout, and gear collapse.
“The video shows the whole landing sequence in great detail,” said EAA Museum Director Adam Smith. “As had been reported by the crew, the airplane executes a normal approach and the touchdown is very smooth. As the landing roll out is completed, the tailwheel is unlocked and a severe shimmy is evident right away. A couple of seconds later, just as the airplane is beginning its turn to exit the runway, the right main undercarriage collapses followed almost immediately by the left.”

Attention at this time is focused on the position of the landing gear as the airplane touched down. Close scrutiny of the tape indicates that the gear was not 100 percent fully extended on both sides.

“On at least one side the downward travel of the gear appears to have stopped slightly short of the normal position,” Smith said.

Meanwhile, officials have a “reasonably good idea” of the repairs that will be needed, and they are working out the best way to go about making them. No timeline has been set for completion of the aircraft inspection or ensuing repairs.

EAA has a long-established B-17 Maintenance Fund that is specifically earmarked for maintenance of the aircraft. To learn more, visit EAA’s B-17 website

They are easy to install . I have installed several retro fits to commuter A/C. Just think about it. Very simple switch with a striker plate that is open when compressed, closed when the gear is fully extended. That doesn’t mean they are murphy proof. I know pilots that put the gear in the up position so exactly after takeoff the gear comes up. However if you hit a bump on the runway and the plane lifts the gear will fold.

Sounds like a dodgy practice to use this system in the way you say some pilots are,I can’t help but feel any pilot doing this is a Danger to him/herself and anyone else who may get in the Way.

The kind of pilot who puts the landing gear control in the up position before beginning his takeoff roll has more dollars than sense. Relying on a small electrical switch to avoid tens of thousands of dollars in damage for no good reason is the height of foolishness. Some guys just don’t belong in cockpits.

They are easy to install . I have installed several retro fits to commuter A/C. Just think about it. Very simple switch with a striker plate that is open when compressed, closed when the gear is fully extended. That doesn’t mean they are murphy proof. I know pilots that put the gear in the up position so exactly after takeoff the gear comes up. However if you hit a bump on the runway and the plane lifts the gear will fold.

I agree, on the ground the stay at the front only supports the force needed to keep the leg in place, while during retraction the wheel moves forward, placing more and more load (if still on the ground) on the retraction screw. They both failed at the same time, so they were probably both fully servicable components without any weak spots.

And the fact that there are no downlock switches is not that uncommon. Having tinkered with a B-25 I know that the situation is similar there. If you would pull the gear lever up (and there is hydraulic pressure available) the gear will go up. There probably won’t be a single aircraft type from that period with a squat switch system (or WOW switch).

B-17 Gear Collapse

From the illustrations referenced earlier it looks as if the gear, when fully down is, somewhere, in an overcentre position – i.e. weight on the gear either pushes the wheels backwards and pulls the main part of the retraction mechanism straight or causes it to hinge away from the retracted position and come up against a stop. Definitely, Once partially retracted the retraction mechanism is bending upwards, pulled by a relatively weak arm, the wheels are moving forwards to put a large upwards load on this (if on the ground!) and there is no way that the vertical strut will not fail or bend, followed by the rest of the gear collapsing.

Tony

Am I understanding this correctly?

Are we saying the B-17 main gear goes up and goes down on an electrically driven scroll? If so does it have up and down lock pins?

Having seen the video, can this really be an inadvertent ‘gear up’ selection?

Under light load conditions, the drop onto the belly was pretty instantaneous. If inadvertant, wouldn’t one expect the aircraft to drop more slowly as the scroll retracts the gear or does the down lock release and the full load on the scroll overload and fail it?

Just curious.

Mark

Well, apparently there is no weight-on-wheels switch on the B-17 originally. A copy-paste from DamienB’s link

Limit switches are mounted for fully retracted and fully extended to electrically stop the motor once the up or down position is reached. There is no other positive lock for the landing gear other than the retracting screw, although the drag strut appears to be in an overcenter position when the gear is extended to assist in holding the gear in a locked position. From an examination of the AAF technical order, there does not appear to be any air-ground switch in the circuit that would require weight-off-wheels to allow the landing gear motors to energize, something that is common on modern aircraft. Whether or not there were any modifications to the EAA’s B-17 that would provide some sort of weight-on-wheels switch to prevent inadvertent gear retraction is unknown.

So, maybe there is nothing on that aircraft to stop the gear being retracted on the ground, and the footage of the gear collapse rather suggests that there was no such device 😮

There is it is called a squat switch

Hi All,

I saw another view of the crash today, and first there is No skid marks behind the Tail Wheel, so this rules out any Tail Wheel shear pin letting go also the plane just flops down like someone grabbed the wrong switch.

Theirs alot more damage then you can see from outside, when the Beely turret breachs a B-17 the whole fus. is twisted, also the Nose Turret pushed up to just under the Bomb Aimers seat.

The Engine Nacells took the brunt of the hit. If anyone wants to lok at photos go over to the Warbird Resource Groups Forum their are up to date photos their.

The latest word I heard is three Months before she’ll even be ready for a Ferrie Flight.

The only thing that seems explainable to me is the possibility of fatigue somewhere?

As for something getting caugth (in terms of foreign body) i highly doubt it if fod plods are done on the runway and taxi ways. They would be extremely foolish not to

Thats my thought, i suppose we’ll have to wait to see what the repair work chucks up

I can’t help thinking that something else must have been the real cause of both jacks breaking simultaneously. The tail wheel is fluttering long before the actual collapse.

Could something have gotten caught up in the tailwheel assembly, which stopped that wheel freewheeling? If that wheel was in a constant braking condition there would, surely, be secondary effects?

Its certainly there Tom..tailwheel was fluttering very noticably. Try the full screen option.

Dunno whether your guys are seeing another video to me, but I can barely see the tailwheel fluttering, let along the gear retracting, as the wing is in the way!

The damage doent look too bad I guess, a bit better than the poor Blenheim

well looking at that site it looks like she’ll be fine, i was suprised to see the sprey mount has come through the fuselarge though. Looking at the rest of the photos the damage doesnt seem that bad

B17 wheels dont fold back as normal they retract forwrds like Dc3s

If this is the case is there any risk to other B-17s flying at the moment i wonder or was it just a bad luck thing.

Let us hope that is was only bad luck. Otherwise it could be that the fleet of B-17 will be grounded again for inspections. And didn’t that happen some time ago for other reasons? Deja-Vu …

J.V.

When the gear fold-up into the wheel-wells the bolts shear, This item is required to be check ever 100 landings.

If you look at the video again please note the gear flod back just like they do when they are retracted.

Lastest word is that the jack screws that enable the gear broke on both sides! Could it be that the fatigue life of the metal was reached at the same time on both sides? Probably the weight of one collapsing killed the second.

Scott

If this is the case is there any risk to other B-17s flying at the moment i wonder or was it just a bad luck thing.

Lastest word is that the jack screws that enable the gear broke on both sides! Could it be that the fatigue life of the metal was reached at the same time on both sides? Probably the weight of one collapsing killed the second.

Scott