Vertical Stab Bolts

[glenn654]

The plans show the bolts to be installed from back to front but the rule of thumb is to install bolts "Top to Bottom and Front to Back".

Anyone know why Van's shows this different method?

Glenn Wilkinson

[tadsargent]

If you are referring to the attach points below the aft deck on the fuse, the nuts would interfere with the rudder leading edge.

Rule number one, follow the plans.
Rule number two, ask questions anytime.

[Ironflight]

Originally Posted by glenn654

The plans show the bolts to be installed from back to front but the rule of thumb is to install bolts "Top to Bottom and Front to Back".

Anyone know why Van's shows this different method?

Glenn Wilkinson

"It's not really a rule, it's more of a Guideline...."

[rv7charlie]

I vaguely recall a story about one of the WW2 aces test flying an early jet, & having a control lock up while in an unusual attitude. Story goes that he was somehow able to free the control & land safely, & when the plane was checked, there was a bolt that was spec'd to be installed head down (or to the rear; I forget), but the assembly guy 'knew better' & installed it 'right'.

[rvbuilder2002]

I didn't look up the specific reference, but I believe the text at the end says "unless the manufacture specifies differently"

[Av8torTom]

Was that a Ghost Busters reference????

[ArVeeNiner]

I had the FSDO inspector last year insist that I turn the bolts around that attach the center elevator hinge bearing to the horizontal stabilizer, even after showing him the drawing. He also didn't like the Nylocks on the seatbelt attach points.

So, I had to order new seatbelt bolts (drilled with cotter pins), swapped them out, and I went ahead and swapped the direction of the bearing bolts after determining that I still had clearance between moving parts. I did have to add washers to get the proper clearance. I'm betting that this is why these bolts aren't per the guidelines.

He came back and signed me off. I guess you get what you pay for!

[rvbuilder2002]

Originally Posted by ArVeeNiner

I had the FSDO inspector last year insist that I turn the bolts around that attach the center elevator hinge bearing to the horizontal stabilizer, even after showing him the drawing.

and I went ahead and swapped the direction of the bearing bolts after determining that I still had clearance between moving parts. I did have to add washers to get the proper clearance. I'm betting that this is why these bolts aren't per the guidelines.

The bad thing about this is, that if the washers you had to add to make everything clear, positioned the bolts so that the bracket is now in barring on the bolt threads, you actually have an installation that is less optimal than it would have been with the bolts reversed.

[rmartingt]

Originally Posted by rv7charlie

I vaguely recall a story about one of the WW2 aces test flying an early jet, & having a control lock up while in an unusual attitude. Story goes that he was somehow able to free the control & land safely, & when the plane was checked, there was a bolt that was spec'd to be installed head down (or to the rear; I forget), but the assembly guy 'knew better' & installed it 'right'.

Originally Posted by Chuck Yeager

I flew a Sabre (F-86 fighter) as a chase plane on those missions which called for me to fly alongside an aircraft being tested. One day, I flew up into the Sierra Nevada mountains to check on a favorite fishing lake. A buddy of mine named Dave Sheltren lived at the edge of the lake, and I came across low to buzz his place, did a slow roll over his house, when suddenly my aileron locked. It was a hairy moment, flying about 150 feet off the ground upside down. But as soon as I let off on the g's, pushing up the nose (actually causing the airplane to head more toward the ground) the aileron unlocked. Very strange. I climbed to 15,000 feet, where it was safer to try it again, and each time I performed that rolling maneuver, the aileron locked. I figured that somehow the wings were bending under stress and locking the aileron. I called General Boyd as soon as I landed and told him I thought I knew how those crashes (the Air Force had lost 3 or 4 pilots for no apparent reasons when their planes crashed while doing rolls down on the deck) occurred, but not why.

The General sent inspectors to take apart my Sabre's wings. They found that a bolt on the aileron cylinder was installed upside down. Crew chiefs in every Sabre squadron were ordered to inspect their airplanes' wings for that upside-down bolt, while an inspection team went to the North American plant and found the culprit. An older man on the assembly line had ignored instructions about how to insert that bolt because, by golly, he knew that bolts were supposed to be placed head up, not head down. Nobody told him how many pilots were killed by his assuming he didn't need to follow instructions.

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[ArVeeNiner]

Originally Posted by rvbuilder2002

The bad thing about this is, that if the washers you had to add to make everything clear, positioned the bolts so that the bracket is now in barring on the bolt threads, you actually have an installation that is less optimal than it would have been with the bolts reversed.

I was going to swap them back during my Condition Inspection but decided to leave them alone. I'll have that on my to do list for the next one.