The forward hinge location:
Crop of Bill Spidle photo
The small circle halfway between the hinge and the leading edge is the retracted end of the unlock indicator.
The aft hinge location:
Crop of Bill Spidle photo
An illustration of the fold joint:
A photo of the fold joint (the closeout of the upper section is primarily a shear web with two different types of stiffeners; the top of the lower section is mostly lightning holes as shown in the illustration above):
The warning pin extended.
Crop of Bill Spidle Photo
This pin appears to be extended when only the wings are folded as well.
The jury struts for the fin and wings (the fin strut folded for storage compactness).
Crop of Bill Spidle Photo
The location of the hole for the bottom end of the jury strut on the 20mm tail:
The "pin" is the gust lock system engaged warning flag.
ReplyDeleteThe gust lock system is manually operated by the yellow striped handle located on the center console.
http://i.ytimg.com/vi/gdTsu6Bewis/maxresdefault.jpg
Looking at the image I provided a link to shows the throttles while in flight with the gust lock system handle in the unlocked position.
Forward of the throttles is the wing fold lever.
It's that flat piece of metal with a finger hold "hump" to the right, right under the safety covered shear-wired external stores jettison switches.
The flat piece of metal that's located near the bottom of the gust lock handle is the throttle stop.
To place the gust lock system in the locked position (grasp the handle and push in the button on the top of the gust lock handle) and then push it over to the left.
Pushing in the button on top of the handle unlocks the handle, when you push it over it extends the warning flags and engages the gust lock system.
Push it over until the gust lock handle is fully engaged.
You'll know it's engaged when the button on top of the handle wants to pop up and the gust lock handle locks in place.
See second picture at the link.
http://www.jali.net/nuw/images/cockpit.jpg
With the gust lock handle fully over to the left and locked in place the flat piece of metal located on the bottom of the gust lock handle rotates over and prevents the throttles from being placed in the take-off position. It's a mechanical safety system to prevent someone from trying to take off with the gust lock system engaged.
If you are doing ground maintenance engine turn you can manually rotate that flat piece of metal out of the way so you can advance the throttles to the military power setting.
Thanks for that. That may be a change from once upon a time. The maintenance manual I have depicts it as a warning flag for the fin-locking mechanism (there is a similar pin that extends from the underside of the wing at the fold joint). However, it hasn't made sense to me that the pin would routinely be extended when the fin isn't folded: you wouldn't want the fin unlocked and not folded and secured.
DeleteThe system is called "The Gust Lock System".
ReplyDeleteWhen you move the gust lock handle to the lowered position the warning flags (beer cans) are extended.
This indicates that the flight controls are locked and that the wing and tail locking pins are mechanically unlocked.
With the wings and the tail folded the wing and tail locking pins are mechanically unlocked and they are retracted.
With the wings and tail spread and the gust lock system engaged (beer cans out) the flight controls are locked and the wing and tail pins are extended but they are still mechanically unlocked.
With the wings and tail spread and the gust lock system disengaged (beer cans in) (ready for flight) the flight controls are unlocked and the wing and tail pins are extended and mechanically locked into the extended position.
The wings and tail are hydro-mechanically locked into place via the wing and tail locking cylinders and hydraulic pressure.
The wing and tail locking cylinders are mechanically locked into place by the gust lock system.
When the wings are folded they are held in place by the automatic wing jury strut system.
There is no such system for the tail, if it's folded there is nothing to hold it in place except it's own weight, gravity and any residual hydraulic pressure inside of the tail fold cylinder.
There are wing and tail jury struts that are used to hold the wings and tail in place.
I have seen Santa Ana winds fold and unfold the tails on A-3's that were not locked into place using a jury strut.