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N4519S Antenna Improvement Project Notes Feb. 21, 2010 Greg Blanck 1. Objective To remove the existing fuselage top mounted “Flying‐V” combination NAV/COMM antenna and bottom mounted “wire” marker‐beacon (MB) antennas. A new set of “blade” style NAV antennas are to be added to the vertical stabilizer, new “bent whip” style COMM antenna and “Blade” style marker beacon antenna will be mounted on the bottom of the fuselage. The new NAV blades will be installed in the vertical stabilizer using original Beech parts provided. Both the new marker beacon and COMM antennas will be installed using existing doublers that are not currently in use. Two new coaxial cable runs to be made from the vertical stabilizer to the panel using provided RG400 cable for NAV1 and NAV2 connections. The new COMM2 connection will be made with an existing RG58 spare cable already in the aircraft. Form 337 and log entries to be made similar to the sample 337 and log entries in this document. 2. Antennas to remove 2.1. Existing “Flying‐V” antenna The existing “Flying‐V” antenna is mounted above the pilot seats. Remove the antenna and fill holes through the existing doubler prior to the painting the aircraft. No new antenna will be placed in this location, but the doubler should be left in place for future use.
Figure 1 ‐ Existing "Flying‐V" installation
Figure 2 ‐ Existing internal Doubler & Connections
Remove antenna, fill bolt and connector holes prior to painting. Leave doubler in place. The coax cables to the existing antenna should be secured and left in place for future use.
2.2. Existing marker beacon antenna The existing MB antenna has one mounting post and two wires fed through the fuselage. Remove the antenna and fill the existing holes prior to painting the aircraft. The existing coax to the MB should be cut and re‐terminated with a BNC connector as it will be re‐used for the new MB antenna.
Figure 3 ‐ Existing MB Antenna installation
3. New Antenna Installation 3.1. Marker Beacon Antenna The new MB antenna (supplied) is a Comant CI‐118 blade style antenna. It will be mounted to an existing doubler plate and connected by a short BNC jumper cable to the existing MB cable. The existing cable will need to be cut close to its current end at the MB antenna and re‐ terminated with a BNC connector.
Figure 4 ‐ Comant CI‐118
Figure 5 ‐ Installation on similar aircraft
Figure 6 ‐ Existing Doubler
The exterior patch plate should be removed and any remaining holes filled prior to painting. If possible, re‐use existing holes when mounting new antenna to the existing internal doubler plate. 3.2. New COMM2 Antenna The new COMM antenna (supplied) is a Comant CI‐112 blade style antenna. It will be mounted to an existing doubler plate and connected to an existing RG58 coax cable already in the correct location (labeled “Future NAV”) in the rear of the aircraft and near the radio stack.
Figure 7 ‐ Comant CI‐112 and installation on similar aircraft
Figure 8 ‐ Existing doubler for COMM‐ external view. Figure 8 ‐ Existing doubler for COMM‐ external view. Remove unused screws and fill prior to paint. Dead bug removal optional…
Figure 8 ‐ Existing doubler for COMM‐ internal view. Note: Doubler is much larger than previous external hole footprint. Remove any unused external screws and fill prior to paint Figure 9 ‐ Existing RG58 Coax run to be used for new COMM2 antenna 3.3. New NAV Blades The new NAV/LOC/GS combined blade antennas (supplied) are Comant CI‐120 blades. The version supplied includes a Comant CI‐120‐4 dual‐output power combiner. The new blades will be mounted to the vertical stabilizer using a collection of original Beech parts as used in the current factory installations. A large access hole must be cut into the stabilizer (which is then fitted with an inspection plate and its associated mounting plate). Internal to the stabilizer an angle and a doubler plate are riveted in place on each side of the stabilizer. The angles and doublers tie to existing internal structure of the stabilizer as shown in the attached drawings.
Note: In the reference photo’s supplied, a Comant CI‐120‐3 single‐output power combiner is used, the dual output version requires two RG400 coax runs to the NAV equipment, the single output version only requires a single cable, but requires an additional splitter. Photo’s, log entries and a 337 copy from an installation done on an identical aircraft are included for reference. 3.3.1. General Location
Figure 10 ‐ General Location ‐ left side view
This left side view of the stabilizer shows the location of the inspection hole cover above an existing line of rivets. Note that only one inspection hole is installed, on the left side of the stabilizer. The angle of the blade antenna should be coincident with the angle of the horizontal stabilizer. The doubler plate is installed between a new “angle” that is riveted in place just above the inspection plate, and an existing line of rivets at the top of the plate.
The existing top‐line of rivets and is the position reference for the top of the doubler plate. Additionally, the plate ties into the rivet line on the vertical “spar” of the stabilizer, which provides the forward/aft alignment position reference for the plate.
Figure 11 ‐ General location‐ right side view
Note the small 4‐hole pattern below the new blade where the signal combiner is mounted. As on the left side, a new row of rivets is visible below the blade which attaches a new angle and the doubler plate.
3.3.2. Inspection hole and cover
The inspection hole is cut to match the shape of the (supplied) cover plate. The mount for the cover plate (supplied) is riveted in place.
New mounting frame riveted in place Access cover mounting frame after installation. Note location of signal splitter mounted to opposite skin.
3.3.3. Angle and doubler installation Each side of the stabilizer gets both an “Angle” and a Doubler riveted in place. Some access for this job is through rear stabilizer spar, so easier to accomplish with the rudder removed. Forward edge of doubler gets joined to the existing vertical spar piece. Existing rivets are removed, new rivets join the doubler and angle to spar and skin using existing holes
New “angle” is riveted to forward and rear spars as well as stabilizer skin and
Top edge of doubler is riveted in place (existing rivet line ends up with twice as many
Aft end of Angle is riveted to rear spar of stabilizer
Note staggered rivet line where upper edge of doubler is attached.
Rivets in this area are replaced to attach new doubler to spar Forward end of angle rivets to spar here
Aft end of angle rivets to rear spar around here. May need small spacer
Aft edge of doubler is roughly here Right side installation is similar using mirror image parts.
View looking up and towards stabilizer center spar. Stabilizer spar
Doubler (right side) riveted to spar Angle (right side) riveted to doubler Left side Angle Antenna BNC cutout. Cable to power combiner
View up and aft towards rear spar showing both newly installed angles
Alternate up/aft view showing right side angle, rivets into rear spar, and doubler rear edge
3.3.4.Blade mounting Blades should be directly opposite each other. Mounting holes are marked with template provided with antenna and holes drilled through skin and doubler. Note horizontal alignment of blade should match horizontal stabilizer line.
3.3.5.Cable Routing Two RG400 coax runs should be made to the power combiner module. The coax routes through existing lightening holes in the spar, and protective grommets should be added to ensure coax doesn’t rub on the spar. (Note: In these images only a single coax is run, the antennas used in this installation require two cables)
Looking up into stabilizer from below, coax routes up into forward section of stabilizer (white wires are tail beacon 12v power supply).
The two coax runs separately feed NAV1 and NAV2. There is an existing CI‐120‐3 power combiner in the aircraft that will be removed once the two new NAV cables are connected. NAV1 takes a single coax directly from the aft signal combiner into the Garmin GNS480 to feed VOR/LOC and GS receivers internal to the 480. No splitter or coupler is required. The coax for NAV2 is connected into an existing splitter that separates the NAV signal for use by the Collins VIR351 NAV receiver and the GLS351 separate glide slope receiver. The new coax just gets connected to the input of this existing splitter.
5. Parts List 5.1. Supplied Parts QTY Part Number 1 95‐110014‐253 1 95‐110014‐383 1 33‐640000‐84 1 33‐640000‐80 1 33‐640000‐83 1 33‐640000‐79 2 CI‐120
Descr. Cover Plate Mount/Doubler for cover plate Angle, Right side Doubler, Right side blade mount Angle, Left side Doubler, Left side blade mount Comant Nav blade antenna (plus related mounting hardware) Signal Combiner Coax jumper to signal combiner ~90’ of RG400 Crimp‐on BNC connectors for RG400 Comant marker beacon antenna Comant “Bent Whip” COMM antenna
1 CI‐120‐4 2 90’ RG400 8 AMP 225395‐6 1 CI‐118 1 CI‐122 5.2. Other required parts TBD
6. Reference 337
7.
8. Reference Log Entry
9. Beech parts manual pages
