EAA 'Aluminum Overcast' B-17 Gear Collapse accident.

[P51DFltLn]

Early photos:
http://www.aero-news.net (the article title is 'How bad was it')

Update information (and more photos) from Van Nuys:
http://www.beechcraft.org/b17-accident/

=R=

So what is being said here is that the gear switch is not easy to flip & this might be a genuine gear failure? We need some b-17 experienced people to set it strait.

[bdk]

http://www.eaa.org/communications/eaanews/040512_b17.html

"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."

[bdk]

So what is being said here is that the gear switch is not easy to flip & this might be a genuine gear failure? We need some b-17 experienced people to set it strait.

I spoke to one of the pilots of the B-17 Miss Angela this past weekend. Their aircraft does in fact have squat switches, but he wasn't sure if the EAA's aircraft was so equipped.

The gear are electrically actuated, and each main gear has its own electric jackscrew actuator. The only common component between the two main gear actuator systems is the switch.

The only likely way for both main gear to retract is if the gear switch is toggled.

[John Beyl]

If the gear didn't extend all the way to the down and lock position then how did they get three green in the cockpit (I guess two in this case because the tailwheel was fixed in the down position)? I would think that the down and locked indicator switchs would be the last to close in both circuits unless they were somehow out of rig and indicated green before the locks were actually overcenter. I don't know about you guys but I'm still confused and wicked happy that she wasn't damaged worse than it was.

[bdk]

If the gear didn't extend all the way to the down and lock position then how did they get three green in the cockpit (I guess two in this case because the tailwheel was fixed in the down position)? I would think that the down and locked indicator switchs would be the last to close in both circuits unless they were somehow out of rig and indicated green before the locks were actually overcenter. I don't know about you guys but I'm still confused and wicked happy that she wasn't damaged worse than it was.

There really isn't an "over-center" in the traditional sense in the B-17. An over-center link in a typical hydraulic landing gear system has a mechanical over-center stop. On the B-17, the threads on the jack-screw are what actually holds the gear in the down position, there is no stop (other than the limit switch that shuts the motor off when it reaches a predetermined point).

I could see that one or both limit switches might not be correctly adjusted, but then the gear would only be a little less or a little more retracted, it still wouldn't allow it to collapse.

Of course I have no more than hearsay information about this incident, I am not an accident investigator, nor do I play one on TV...

[Tony C]

I've just been reading the news article in Aeroplane Monthly and the end of the article states "Basic repairs were to be made before a ferry flight to Chino or Oshkosh for refurbishment"

As I'm not an engineer, is it possible to make "basic repairs" which would allow the airframe to fly as the photograph in AM, shows that the Belly Turret mountings were punched through the upper fuselage and I would have thought that this would have damaged the integrety of the airframe?

[bdk]

I've just been reading the news article in Aeroplane Monthly and the end of the article states "Basic repairs were to be made before a ferry flight to Chino or Oshkosh for refurbishment"

As I'm not an engineer, is it possible to make "basic repairs" which would allow the airframe to fly as the photograph in AM, shows that the Belly Turret mountings were punched through the upper fuselage and I would have thought that this would have damaged the integrety of the airframe?

Yes, temporary repairs can be made in some instances. This would allow issuance of a Ferry Permit by the FAA to get the aircraft to a suitable location for permanent repairs.

[Dan K]

Which brings me to the topic of ferry pilots in general. I had the experience of examining a PV-2 post ferry flight. Several pulleys of the flight control system were frozen solid--the pilots had basically been pulling the control cables through them anyway.

You couldn't pay me enough to go up in a knowingly compromised aircraft.

So are ferry pilots overly-brave, overly-confident, or overly-nuts?

(My apologies to any ferry pilots, active or otherwise, who may frequent this board )

[bdk]

I had the experience of examining a PV-2 post ferry flight. Several pulleys of the flight control system were frozen solid--the pilots had basically been pulling the control cables through them anyway.

I think you will find that this is a common occurrence on older aircraft, especially those which don't fly much or spend significant amounts of time out in the weather.

If the pulleys or cable rollers don't significantly change the direction of the control cable, the cable tension doesn't put much of a normal force on them- so the cables just slide over them if they are not adequately lubricated. Many aircraft also have fixed micarta fairleads in the control sytems so the cables just drag over them anyhow.

I'm sure the pilots wouldn't have flown the plane if they experienced binding in the controls during pre-flight checks.

Also, the pilot is not necessarily the mechanic certifying the aircraft as airworthy for the ferry flight. The pilot does a walkaround inspection for obvious flaws and check the controls for feedom of movement. The pilot is not expected to climb into the tailcone as part of his pre-flight inspection.

I doubt that ferry pilots are braver than anyone else. Many ferry pilots deliver brand new aircraft to their owners, not just antique aircraft being repositioned to alternate maintenance locations.