Elevator Stab Install - Part 3

With the stab completed the excerise is to install it onto the air-frame. Locating the front and rear mounting brackets these were reamed 3/16'' and 1/4'' as required using a tapered reamer and battery drill, finally the mounting holes in the rear bulkhead were reamed a 1/4''. 

As the mounting bolts project perpendicular from the face or the spar the holes were reamed parallel to the side of the fuselage to aid installation of the bolts. 

Reaming mounting holes bulkhead

Two tapered spacers are provided with the kit to correct the angle between the front spar of the stab to bulkhead. A vernier was used to locate the thickest section of the spacer which was then marked with yellow paint pen and finally the holes reamed to a 1/4'' using the tapered reamer.

The mounting brackets are fixed to the spar using the specified AN3 bolts and washers through the access panel. 

Next the specified AN4 were fitted through the spar and the lower mounting with the spacers fitted between the spar and the bulkhead and the nuts installed by finger. 

Note: It was found that all bolts needed to be loose to allow the AN4 bolts to be inserted into the bulkhead.

With the assembly bolts still loose the spacer was rotated until the previously marked high points and aligned with the side of the fuselage, at this point all bolts were nipped up ensuring the spacers remained in the correct alignment. 

Setting the Stab Incident

"Doctor will it ever be right?"

"Nurse, I don't know but lets keep 
adding tubes with that blue stuff !!

The fuselage was leveled on both the longitudinal axis and cross axis with the time proven method of water gauges chosen. A twelve [12] meter length of 3 mm tube was purchased and filled with a mixture of wet water [water with a drop of detergent] and blue food dye. 

There were four required in total - two [2] for the fuselage and two [2] for the stab. These were installed along the fuselage using the top rivet line of the fuselage and then across the fuselage using the same reference. 

Next the center line of the outer stab ribs were marked by splitting the verticals at both ends, a tube was installed and repeated across the stab spar.

With the fuselage leveled then the stab was leveled across the fuselage using a 10 kg bag of sand to apply the necessary torque.

FUSELAGE SET-OUT

The angle of incident for the stab is zero [0] degrees, using a water gauge located on the reference line on the outer rib the correct angle is established and then both mounting holes were marked using a transfer punch.

Note: This required the removal of the stab assembly to gain the access to drill the holes square.

Note: This task did require removal of the stab again.!