July 2012
I ordered an Ashby fiberglass glareshield from Aircraft Spruce along with right and left windshields halves from Great Lakes Aero Products. (Yes, I decided to replace the right side windshield as well.)
FAA regulations require the supervision of an A&P mechanic for the replacement of the aircraft windshield, so I enlisted the services of my A&P father. He has been involved in almost everything that I have done to 61 Tango.
Unlike the side windows, the windshield is removed from the outside of the aircraft. Removal of the windshield required removal of the lower collar molding from the bottom of the windshield, removal of the trim strip from between the windshield halves, and finally, removal of both halves of the windshield. Then we removed the old cloth glareshield covering and the instrument panel overlay which includes the eyebrow that wraps around to the glareshield.
The Ashby fiberglass glareshield requires custom trimming and fitting. To accomplish the proper fit, we made a poster board template of the new glareshield and trimmed and test-fitted the poster board template until it looked acceptable. Then we used the poster board template to trim and fit the fiberglass glareshield. The glareshield itself required additional trimming and numerous test fits until we were able to achieve a satisfactory result.
Additionally, we had to modify the instrument panel overlay to make it fit under the new glareshield, as well as locate and cut holes in the glareshield for defroster vents, handholds and the compass mount.
It was a lot of work, but we ended up with a professional-looking installation.
WINDSHIELD INSTALLATION
Installing the new windshield was much more difficult than removing the old one. Piper uses foam tape applied to the edge of the windshield to pad and cushion the windshield from the airframe. After installation, sealant is applied to the seam around the windshield to form a seal.
The hardest part of the installation is getting the windshield and foam tape to slide into the channel that runs along the sides and top of the windshield frame. We had to resort to a wood block and hammer to get the windshield seated in the channel. After that, it was easier: apply sealant to the lower collar and middle trim strip, and screw in place.
I developed a method for applying a nice, neat bead of sealant to the windshield seam after installation. I applied a two-inch wide band of masking tape over the seam around the entire windshield. Using a razor blade knife, I cut the tape by tracing the edge of the windshield frame.
I left the tape attached to the frame in place and removed the tape from the windshield and reapplied it to the windshield approximately 1/8 inch from the windshield frame. Next, I applied water-based sealant to the space between the tape, smoothed the sealant with a wet finger and a damp rag, and let it cure. When I removed the tape, I had a bead of sealant that looked more like a gasket.
NEW OAT GAUGE, TAILCONE REPLACEMENT
Earlier I mentioned that I would explain the replacement of the OAT gauge. Six-One Tango had the remains of an old wire-type ADF antenna mounted above the cabin, directly behind the windshield. I wanted to remove the old antenna before repainting 61 Tango and planned to reuse the existing hole for a temperature probe. The new probe would be directly behind and within inches of the old probe location in the windshield.
I purchased a Westach OAT gauge, FAA approved for use in a certificated aircraft, with a remote temperature probe from Aircraft Spruce. We installed the two-and-one-quarter inch temperature readout in the instrument panel, and the probe in the top of the cabin. We ran the wiring for the probe through the center windshield post.
The upper and lower half of 61 Tango’s tailcone were originally manufactured out of Royalite, basically an ABS styrene plastic that doesn’t hold up well to the environment and is prone to cracking. Six-One Tango’s upper and lower tailcone halves had developed many cracks and were almost unusable.
I purchased fiberglass replacement upper and lower tailcone halves from Met-Co-Aire. After receiving the parts, my father and I removed the old tailcone and test-fit the new parts. They fit perfectly; no trimming necessary. All we had to do was locate and drill mounting holes in the new parts and install them.
The tailcone is held in place with screws and clip nuts. To locate the new holes in the replacement parts, we used a strap locator tool that I purchased from Met-Co-Aire. The tool is basically two strips of metal, spot welded together at one end.
At the opposite end of one strip there is a point that is inserted into the existing hole in the airframe. The other strip has a bushing for drilling a pilot hole. The bushing is located on the strip such that it is aligned with the point on the end of the other strip.
The new part is then positioned between the two strips and in the proper position in relationship to the airframe. Drilling through the bushing produces a pilot hole in the new part exactly in line with the hole in the airframe. This tool worked beautifully and we easily replaced 61 Tango’s tailcone.
FAIRINGS, STABILATOR TIPS
Six-One Tango’s aft dorsal fin fairing had a small crack at one of the screw locations and the forward dorsal fin fairing was badly deteriorated. Again, I purchased fiberglass replacement fairings from Met-Co-Aire and again, they fit perfectly.
The aft dorsal fin fairing is held in place with screws and clip nuts just like the tailcone, however, the forward dorsal fin fairing is riveted in place. My father and I drilled out the old rivets, located and drilled holes in the new fairing, and riveted it in place.
Next was the replacement of 61 Tango’s stabilator tips. The stabilator tips are made of fiberglass and had developed many stress cracks that had been stop drilled throughout the years. Walt at Prestige Aircraft had advised that at approximately $375 a pair it would be cheaper to replace the stabilator tips than to recondition them. As a now-loyal customer, I ordered the tips from Met-Co-Aire.
Mounting the stabilator tips required locating and drilling holes in the new tips. To accomplish this my A&P helpers and I removed the old tips from the stabilator and applied a six- to eight-inch-wide band of masking tape to the upper and lower surfaces of the stabilator just inboard of the existing mounting holes.
Using a straight edge, I constructed intersecting lines through each of the holes. Then I calculated the minimum distance from the inboard edge of the new tips to the center of the new holes that would provide the required edge distance for the holes. That turned out to be approximately one-half inch.
I marked a line on the stabilator running from forward to aft and one-half of an inch inboard from the center of the existing holes. Next I attached two straight edges to the upper and lower surfaces of the stabilator, parallel to the stabilator spar and extending beyond the outboard of the end of the stabilator. The straight edges were held in place with tape.
Next I positioned the new tip on the stabilator such that the outboard end of the tip was positioned equidistant from the upper and lower straight edges and installed to a depth of one-half-inch or more onto the stabilator. I retraced the intersecting lines for the front upper and lower holes onto the new tip, locating the center for the new holes. Then I removed the tip and drilled the two front holes. A step drill works great for drilling into fiberglass.
I screwed the tip in place using the two front holes, and then I properly positioned the aft end of the tip and located the centers for the aft upper and lower holes. I removed the tip and drilled the two aft holes. Then I remounted the tip using the forward and aft holes, double-checked the fit, located the rest of the holes and completed the installation.
PERFORMANCE UPGRADES
Six-One Tango’s wingtips are also made of fiberglass and had developed many stress cracks, and like the stabilator tips, would be cheaper to replace than to recondition. I also had a desire to enhance 61 Tango’s short-field capability.
I called upon Art Mattson at AMR&D for his recommendation on airframe modifications that would increase short-field performance. His number one recommendation was Hoerner style wingtips manufactured by Met-Co-Aire, followed by AMR&D’s own vortex generator kit and aileron/stabilator gap seal kit. Mattson did not recommend flap gap seals for short-field performance, as they may interfere with the aerodynamics of the Cherokee’s Fowler flaps.
The Met-Co-Aire Hoerner style wingtips were installed using the same method used to install the stabilator tips, except that a single straight edge was used to keep the upper surface of the wingtip parallel to the upper surface of the wing.
READY FOR PAINTING
With the entire list of items completed, 61 Tango was ready to be delivered to Prestige Aircraft. I decided to keep the original 1972 paint scheme with some minor tweaks: I planned to change the lower pinstripe and registration numbers from gold to blue. Walt suggested painting the wingtips blue versus leaving them white, and painting the tops of the wheel pants blue.
I delivered 61 Tango to Prestige Aircraft on Nov. 1, 2009. Walt began prepping the aircraft on Nov. 3 as we worked out our final paint scheme and color selections. Walt had included in his price the installation of AMR&D’s vortex generator kit and Knots 2U’s wing root fairings. Walt e-mailed me on a weekly basis and sent pictures as the work progressed. By Jan. 6, 2010, the makeover of 61 Tango was completed.
When I saw 61 Tango, I was absolutely thrilled. I was amazed by the quality of the paint and the attention to detail. She truly did look as good, if not better, than a new aircraft!
I’ve noticed some major improvements in 61 Tango’s performance as a result of the modifications. Maximum cruise speed at 6,500 feet MSL and 75 percent power is approximately 150 mph—8 mph better than the book. Full flap stall speed has been lowered from the book value of 54 mph to approximately 42 mph. Aileron response has been greatly improved; it’s especially noticeable at low airspeeds.
Tim O’Brien is a Piper Flyer Association member. He submitted this story so that other members may benefit from his experience. He flies 61 Tango in and around upstate New York. Send questions and comments to editor@www.piperflyer.com.
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