SNOW ENGINEERING CO. 

### ENGINEERING NUMOER
WICHITA FALLS, TEXAS ~
SERVICE LETTER #80GG DATE OF 1 1/5/05 *Revised to include **Revised 12/21/05 SUBJECT: Inboard Spar Structure Replacement
MODELS: AT-802, AT-802A
ELIGIBLE SERIAL NUMBERS: 802-0001 AND SUBSEQUENT

TJf7R3D(lCF'- 7 11/20/05

This service letter is to provide instructions for replacing the p/n: 20603-1/-2 or p/n: 20978-1/-2 lower spar caps. An assembly consisting of upper and lower spar caps, inboard two webs, and web plates is provided by the factory. For s/n 802-0092 and subs. the p/n 20977-1/-2 upper spar caps and p/n 20976-1/-2 attach blocks will be removed and reinstalled. For s/n 802-0001 through 802-0091 the p/n 20604-1/-2 spar caps and p/n 20602-1/-2 attach blocks will be replaced with new p/n 20977-1/-2 upper spar caps and p/n 20976-1/-2 attach blocks. The factory will furnish a new p/n 20994-2 fail safe plate for serial numbers 0001 through 0101 and reuse the existing 20994-2 plate on serial numbers 0102 and subs. The spar assemblies will be drilled to match the plate.
A. AIRCRAFT PREPARATION: l. Check the kit to assure the lower spar caps and splice blocks are matched sets. The lower caps and blocks are matched by serial number. There is an aluminum tag attached to the lower caps and splice blocks that has the matched set serial numbers stamped in them. Ensure that these serial numbers match the serial numbers in the lower spar caps and splice blocks.
2. Rinse out hopper if required. Open hopper lid and gatebox door the day before to allow air circulation.
3. Drain the wing and header tank fuel. Wash the airplane.SNOW ENGINEERING CO. 

### I ENGINEERING NUMBER
WICHITA FALLS, TEXAS REPORT C 

# 1
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SERVICE LETTER #80GG DATE I Jee t5elow
*Revised to include 802A-0067 11/20/05 **Revised 12/21/05 AIRCRAFT PREPARATION (Cont'd):
4. Remove the following: Removable skins, hopper gatebox and adaptor, front hopper, wing root fairings, wing inspection covers, flaps, ailerons, and any other parts required. See your Owners Manual for removal instructions.
5. Disconnect the aileron pushrod from fuselage idler. Remove wingtip if a painting fixture is to be installed.
6. Disconnect the wiring, the pitot tube plumbing, and fuel vent lines in the fuselage. Be sure to check the marks on the wires so that reassembly will be easy. Remove the fuel line from the tank fitting to the header tank and remove the tank fitting and the drain valve from the header tank. Use masking tape to cover the ends of the tubes, so that no contamination is allowed into the fuel or pitot system.
7. With hopper removed, inspect and make repairs to the firewall if needed. Inspect spray pump fittings and fuselage structure for cracks. Check for Service Letter compliance: #156 (Rudder Pedal Bushing), #166 (Brake Master Cylinder).
8. If the factory is to replace spar caps, bring all spar splice blocks and bolts, and fail safe plate and bolts.
B. WING REMOVAL FROM AIRCRAFT: 1. Support both wings with wing jacks at the tie down ring. If no wing jacks are available a pair of tall saw horses may be used in the area of the tie down ring. Place a scrap of carpet between the wing and the top of the saw horse so as not to scratch the wing. Construct two .50 inch thick* blocks and insert them in between the lower longeron and the lower spar cap of each wing. Protect the frame and the spar cap from being scratched by the blocks with duct tape.
2. Unbolt and remove the wing attach angles. Remove the two AN6 bolts in the 20618-1 plate located at the top of the center splice.C SNOW ENGINEERING C0. 

# I ENGINEERING N
WICHITA PALLS, TexAS 

### REPORT 

## 0

SERVICE LETTER #80GG DATE
*Revised to include 802A-0067 11/20/0 **Revised 12/21/05 WING REMOVAL FROM AIRCRAFT (Cont'd): 3. Remove the center splice tube-nut bolts and unbolt both the upper and lower splice blocks. Remove the splice blocks. Be careful not to damage the holes in the upper splice blocks when removing the bolts, since these blocks are to be re-used. *Aircraft built after S/N 802-0139 may have a.59 thick block on L/H side, .50 thick R/H side. Before removing the wings measure the space between the lower longeron and the lower spar cap on each side. Prepare blocks to match this space. 9. Make sure the blocks inserted between the lower spar cap and the lower longeron are still in place. Mark the aft face and unbolt the fail safe plate and remove it. You may have to adjust the saw horses or jacks on the wings to take the bolts out of a bind. The bolts should come out with a very light tap from a small hammer. Be careful not to damage the holes when removing these bolts. 5. Position a saw horse under the wing a couple of feet out from the root. Remove the rear spar attach bolt while supporting the wing. Double check that all the wires, tubes, and controls are removed or disconnected from the wing and that there is nothing to keep the wing from being removed from the fuselage. Remove the pitot tube from the left wing. It takes a number of strong men to lift the wing and remove it from the fuselage due to the wing weighing approximately 800 pounds. Remove the wing from the fuselage and set it on the saw horses.
G LEADING EDGE REMOVAL: 1. This rework involves removal of many existing rivets. To remove a rivet, first determine the size of the rivet. Select the proper drill size for the rivet to be removed. This is the same size drill used for drilling a hole for a new rivet. Drill the head just deep enough to remove the rivet head from the shank. Do not drill through the hole as this will often elongate the hole. The shank is then tapped from the hole with a pin punch. If you have damaged or elongated holes you may increase the rivet one size. There are a few 5/32" rivets that attach the leading edgeSNOW ENGINEERING CO. 

### I ENGINEERING N

WICHITA FALLS, TEXAS REPORT 

### ~
SERVICE LETTER #80GG DATE 1/5/05 1 4 18 *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 WING LEADING EDGE REMOVAL (Cont'd): skin to the ribs on planes with rib doublers. Mark these locations. All other rivets are 1/8".
2. The three inboard leading edge skins can be removed as a unit. Drill and remove all the rivets in the three inboard leading edge skins. This includes all the rib rivets, main spar flange rivets and the skin lap rivets between the #3 and #4 leading edge skins. To complete removal of the 3 inboard leading edge skins you may need to take a box knife and cut the sealant from the skin laps. Remove the lift detector from the left wing before removing the number 3 leading edge skin.
3. Mark the leading edge ribs #1, #2, #3, etc. and remove them from the main spar. Inspect these for cracks and replace as necessary. If more than 3 ribs are cracked per wing, install the P/N 21062-1/-2 doubler per drawing 21107 in both wings on #5, #6, #7, #8, #9, #10, #11, #12 nose ribs.
4. Remove wire harness, clamps, and attaching hardware from spar to Station 191.
D. FAIL SAFE PLATE MODIFICATION: 1. The p/n 20997-1 or -2 fail safe plate (if installed) was used on s/n 0001 through 0091. It will not fit the new half-spars and is to be discarded. Half spars from the factory will come with a new p/n 20994-2 fail safe plate that is drilled and reamed with the new half spars.
2. For s/n 0092 and up, if the p/n 20994-1 or -2 fail safe plate has been installed, ship it to the factory while the half spars are being built. The factory wi11 convert a-1 to a-2 configuration if required, and drill the half spars to match the plate. +*SNOW ENGINEERING CO. 

### ENGINEERING rMB18 WICHITA FALLS, TEXAS 

# I REPORT 

## 171 9

SERVICE LETTER #80GG DATE 1 1/5/05 1 5 1£ *Revised to include 802A-0067 11/20/0! **Revised 12/21/05 E. OPTIONAL LEADING EDGE INSPECTION HOLE INSTALLATION INSTRUCTIONS: 1. To facilitate the possibility of future inspections of the inboard area, an optional inspection hole may be installed as shown on drawing SK551-1 through SK551-5.
2. Parts list for the inspection cover installation are as follows:
2 ea. SK551-2 Doubler 2 ea. SK551-3 Cover Plate 54 ea. 90013-4 Screw 54 ea. 130800-18 Nut (Monadnock) 1 ea. SK551-5 Template

F. MAIN SPAR REMOVAL: 1. A main spar assembly consisting of the parts shown on the next page is provided by the factory. It will be necessary to remove the original assembly from the wing for the first 235 3/8 inches of span.
2. The rivets attaching the main spar to the main ribs, fuel tank ends, and fuel baffles will require removal. Take a black felt marker and circle the rivets to be removed.
3. Use a cold chisel and a hammer to cut the lock collars from the lockbolts in the upper spar cap extension. Use a 1/8" pin punch to remove the lock bolts.
4. Remove the lockbolts in the upper spar cap extension to the outboard end at WS 262 112. Use a felt marker to identify the shown side of the 20616-1 splice blocks. Example: "Upr-Aft-Inbd", and "Upr-Fwd-Inbd". Remove the spar cap extension, and return it to the factory.
5. The No. 2 spar web, p/n 20410-1/-2, that starts at WS 138.0 and goes to WS 235 3/8 is to be removed and returned to the factory as well. The factory will use it in the replacement assembly if it is in good shape and the holes line up with mating parts. Remove lockbolts and rivets only where required for removal from spar. *

*SNOW ENGINEERING CO. 

### ENGINEERING NUMBER
WICHITA FALLS, TExAS REPORT #80GG ORDER X MODEL TITLE BY CHK'D See Below

SERVICE LETTER #80GG Leland Snow SERIAL DATE See Below PAGE OF 1/5/05 6 18 *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 MAIN SPAR REMOVAL (Cont'd):
6. Break the inboard part of the main spar loose from the fuel tank sealer. One way is to start on the inboard end pulling the spar forward and cutting the sealer loose with a carpet knife as you move outboard. The factory uses fixtures bolted to the floor that position the wing vertically, and uses a chain hoist overhead to pu11 the spar loose from the wing.
7. With the spar removed, inspect the main ribs and fuel tank ribs for cracks. Main ribs that are cracked should be replaced or repaired per SK547. Attachment of replaced main ribs to the rear spar may be with CR2173-4 rivets. Inspect the rear spar plate fuselage attach hole for wear or elongation, as this would be a good time to change it if required. Check attach bolt torque.
8. Clean off the fuel tank sealer from the rib angles that attach to the front spar. Clean out any sealer that appears deteriorated and reseal in accordance with the OWNERS MANUAL.
9. INSPECT step A-7, steps C, D, E, and F. Insp.26

2] SNOW ENGINEERING CO. 

### ENGINEERING NUMDER WICHITA FALLS, TEXAS 

### REPORT C #80GG MOD[L BV See Bel SERVICE LETTER #80GG DATE 1 1/5/05 I 7 *Revised to include 802A-0067 11 05 **Revised 12/21/05 

### I G. REPLACEMENT SPAR CONFIGURATION:

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# I ENGINEERING WICHITA FALLS, TfixAS 

### REPORT 

## C

SERVICE LETTER #80GG DATE

*Revised to include **Revised 12/21/05 REPLACEMENT SPAR CONFIGURATION (Cont'd): NUMBER



### 1 8 02A-0067 11/20

1. The factory replacement assembly will consist of the following: (Serial Numbers 0001 through 0091) L/H Wing listed, R/H Opposite
1 ea. 20409-1 Web * 1 ea. 20977-1 Upper Spar Cap* 1 ea. 20413-1 Plate 1 ea. 20976-1 Splice Block 1 ea. 20413-2 Plate 1 ea. 20976-2 Splice Block 1 ea. 20413-3 Plate 1 ea. 20994-2 Fail Safe Plate 1 ea. 20413-4 Plate 1 ea. 20616-1 Splice Block 1 ea. 20413-5 Plate 1 ea. 20616-2 Splice Block 1 ea. 20629-1 Plate 1 ea. 20630-1 Plate * These parts have a-2 p/n 1 ea. 20633-1 Plate for the R/H wing. 1 ea. 20634-1 Plate ** This part has a-1 p/n for 1 ea. 21082-1 Splice Block the R/H wing 1 ea. 21082-2 Splice Block 1 ea. 21083-1 Lower Spar Cap * 1 ea. 20612-1 Lower Spar Cap Extension * 10 ea. 20418-1 Angles @ sta. 34 5/8, 38 13/16, 48.0. 58.0, 68.0,

79 3/16, 91.0, 103 1/4, 115 7/8, 128 5/16* 4 ea. 20422-1 Angles @ sta. 141 1/8, 153 1/8, 165 15/16, 179 3/4 2 ea. 20419-1 Angles @ sta. 206 13/16, 220 5/8 1 ea. 20288-500 Lockbolt Kit 1 ea. 20631-500 Hardware Kit 1 ea. 20975-500 Hardware Kit In addition to the above, the replacement assembly will consist of the following parts salvaged from the original wing:
1 ea. 20410-1 1 ea. 20612-2 2 ea. 20616-1 1 ea. 20632-1 1 ea. 20633-1 1 ea. 20634-1 Web *

Spar Cap Extension - Upr ** Splice Block - Upr Plate Plate - Upr Plate - Upr The salvaged parts are to be inspected visually for cracks, cleaned, sanded, and refinished per PS 102.SNOW ENGINEERING CO. WICHITA FALLS, TEXAS 

### ENGINEERING 

# [7

NUMBER

REPORT 

# =

TITLE BY C6]RI SERVICE LETTER #80GG DATE

*Revised to inc1L **Revised 12/21/05 REPLACEMENT SPAR CONFIGURATION (Cont'd): SERIAL



### 1 9 e 802A-0067 /20/O5

2. For the 308 gallon fuel tanks, the spar is configured as shown on drawing 20766. For 380 gallon fuel tanks the spar is configured as shown on drawing 20677.
1. The factory replacement assembly will consist of the following: (Serial Numbers 0092 and subs.) L/H Wing listed, R/H Opposite
1 ea. 20409-1 Web * 1 ea. 20616-1 Splice Block 1 ea. 20413-1 Plate 1 ea. 20616-2 Splice Block 1 ea. 20413-2 Plate 1 ea. 20413-3 Plate * These parts have a-2 p/n 1 ea. 20413-4 Plate for the R/H wing. 1 ea. 20413-5 Plate ** This part has a-1 p/n for l ea. 20629-1 Plate the R/H wing 1 ea. 20630-1 Plate 1 ea. 20633-1 Plate 1 ea. 20634-1 Plate 1 ea. 21082-1 Splice Block 1 ea. 21082-2 Splice Block 1 ea. 21083-1 Lower Spar Cap * 1 ea. 20612-1 Lower Spar Cap Extension * 10 ea. 20418-1 Angles @ sta. 34 5/8, 38 13/16, 48.0, 58.0, 68.0, 79 3/16, 91.0, 103 1/4, 115 7/8, 128 5/16* 4 ea. 20422-1 Angles @ sta. 141 1/8, 153 1/8, 165 15/16, 179 3/4 2 ea. 20419-1 Angles @ sta. 206 13/16, 220 5/8 1 ea. 20288-500 Lockbolt Kit 1 ea. 20631-500 Hardware Kit In addition to the above, the replacement assembly will consist of the following parts salvaged from the original wing:
1 ea. 20410-1 Web * 1 ea. 20977-1 Spar Cap - Upr * 1 ea. 20612-2 Spar Cap Extension - Upr ** 2 ea. 20616-1 Splice Block - Upr 1 ea. 20632-1 Plate 1 ea. 20976-1 Splice Block - Upr only ** 1 ea. 20633-1 Plate - Upr 1 ea. 20976-2 Splice Block -Upr only **SNOW ENGINEERING CO. 

### ENGINEERING N
WICHITA FALLS, TEXAS 

### REPORT =

SERVICE LETTER #80GG DATE
*Revised to include 802A-0067 11/20/05 **Revised 12/21/05 REPLACEMENT SPAR CONFIGURATION (Cont'd): 1 ea. 20634-1 Plate - Upr 1 ea. 20994-2 Fail Safe Plate The salvaged parts are to be inspected visually £or cracks, Cleaned, sanded, and refinished per PS 102. 2. For the 308 gallon fuel tanks, the spar is configured as shown on drawing 20766. For 380 gallon fuel tanks the spar is configured as shown on drawing 20677.
H. MAIN SPAR ATTACHMENT: l. Review the drawings supplied in the kit. Determine which drawings are applicable to the fuel tank size of the plane you are working on and keep these handy. File the drawings that are not applicable.
2. Position the new spar assembly on the wing. Check the holes in the upper spar cap extension to see if they line up with the holes in the spar web. If there is not perfect alignment, then drill new holes .159 per drawing SK604 through the spar cap extension and spar web. Enlarge holes to .1875, then chase to .189. There should be as many new lockbolt holes as there were originally. Chase the old holes .189 that did not line up, as you will be installing lockbolts in the old holes as well as the new holes per Step #9. Chase some spar web to baffle or tank end holes .189 and cleco the web to the baffles or tank ends. At each rib or baffle station, the holes in the angle that attaches to the baffle or tank end should line up with the holes in the new spar assembly. If the holes do not line up, mark the location of the angle that must be replaced, and replace it when the spar is removed.
3. The lower spar cap extension will need to be drilled .189 to match the existing web from station 235 3/8 to 262 112. To do this, remove the doublers around each inspection hole in the lower wing skin for better access. With a.189 drill, mark the lower spar cap at each location for a lockbolt by drilling into it from the aft side of the spar web. 

### **SNOW ENGINEERING CO. I ENGINEERING "uMBER

WICHITA FALLS , TExAS REPORT 

### ~ d X TI7LE By

SERVICE LETTER #80GG Le] DATE OF *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 MAIN SPAR ATTACHMENT (Cont'd):
4. Use some "C" clamps through the 4-inch holes in the outboard spar web to clamp the upper and lower spar caps to the spar web. Back drill .189 through the existing lockbolt holes in the aft side of the spar just deep enough into the aft face of the small leg of the lower spar cap to locate the holes. These holes will be drilled in the drill press later. It may be necessary to drill out rivets attaching the lower main skin to gain access by peeling the skin back.
5. Remove the spar assembly and place it on a drill press table. Turn the spar assembly over with the forward face down. Drill the lower spar cap small leg .189 through the holes located in step 4.
6. Remove any drill shavings from inside the wing and fuel tank area. Reinstall the spar assembly with many clecos.
7. Consult drawing 20288 for location of the lockbolts.
8. INSPECT steps 6 and 7. Insp.
9. Install all the lockbolts per Process Spec #181. Install all the NAS1446-X lockbolts through the upper and lower spar caps and cap extensions. Install all the MS20470AD6 rivets through the wing rib angles. Use drawing 20288 to determine proper fastener locations.
10. INSPECT step 9. Insp.

I. REINSTALLING THE LEADING EDGE:
1. Install the wiring harness clamps and hardware that were removed in step C4.
2. Match dri11 the top and bottom main spar flange to the center wing skins. Use drawing 20380 to determine the proper drill size.
3. Use a felt tip marker to mark the center of the flange of any new leading edge ribs. Install the old leading edge ribs to theSNOW ENGINEERING CO. 

# I ENGINEERING 

# [7

NUMBER

WICHITA PALLS, TExAS 

### REPORT 

## 0

SERVICE LETTER #80GG DATE 11/5/05 1 12 18 *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 REINSTALLING THE LEADING EDGE (Cont'd): spar web in the place they were removed from as shown on drawing 20380. Install any new ribs as shown per drawing 20380. Add a rivet of like size between the two attaching rivets in places that show fretting between the spar web and rib. 4. Install p/n: 20620-1, 20650-1, and 20236-2 leading edge reinforcement doubler (saw tooth doubler). Using an awl or pin punch, align holes with spar flange. S. Locate the leading edge skins over the leading edge ribs. Cleco the leading edge skins to the upper spar flange at each leading edge rib location. Cleco the upper surface of the leading edge skin to all the old ribs. Locate any new ribs so that the rib flange center mark shows through the leading edge skin holes on the upper surface. Back drill the new ribs to match the upper surface of the leading edge skin. It is easier to install the leading edge rib to skin upper surface rivets with the lower surface of the leading edge skin hanging, so install these rivets now as shown on drawing 20380. Be sure and note the location of the 5/32 rivets marked in step C1. Add some p/n 20098-1 or -2 shims where required between the ribs and skin to keep the surface smooth.
6. Pull the lower surface of the leading edge skin to the lower main spar flange and cleco it to the flange at each rib location. Align the leading edge ribs with the holes in the lower surface of the leading edge skin and cleco them in place. Locate any new ribs so that the rib flange center mark shows through the leading edge skin holes on the lower surface. Back drill the new ribs to match the lower surface of the leading edge skin. Rivet the leading edge skins to the ribs as shown on drawing 20380. Add p/n 20098-1 or -2 shims as required.
7. Rivet the upper and lower spar flanges to the wing skins as shown on drawing 20380. It is very important to use the correct size rivets along the spar flange. If rivet holes are oversize, the next larger size rivet may be installed.
8. Inspect leading edge installation. Insp.SNOW ENGINEERING CO. 

### ENGINEERING NUMBER
WICHITA FALLS, TEXAS ~ BY CHR'D I See Be SERVICE LETTER #80GG DATE I1/5/05 1 13 *Revised to include 802A-0067 11 /05 **Revised 12/21/05 J SEALING THE FUEL TANK AND PAINTING THE WINGS: 1. Install painting fixtures on each end of the wing.
2. Clean the fuel tank of all drill shavings. Seal the fuel tank as described in the Owners Manual Maintenance Section. Seal all the skin laps with PRC 1422 A2 by masking a 1/8 stripe at the laps and painting on the sealer with an acid brush. Make sure that the inside of the wing is clean and well sealed.
3. Install the tank inspection covers with PRC 1422 B2. After the sealant has cured, pressure test the tank seal to 1.5 PSI air pressure. Do not apply more pressure than this, as damage may occur. The tank should hold this 2 or more hours.
4. Make sure the tank does not leak before repainting the wings. Otherwise the cover plates will not look good from having been removed and replaced after being painted. Consider testing the wings with fuel before painting.
5. Repaint the wings, using materials and procedures listed in the OWNERS MANUAL.
INSPECT Insp.

K REINSTALLING THE WINGS ON THE FUSELAGE:
1. Set the wings on the saw horses adjacent to the fuselage. Set the outboard end of the wing up on the jack or the tall saw horse. Make sure the aileron push tube is in the wing and that the boot and boot ring are installed.
2. Grease the rear spar attach fittings and bolt. It will take several men to place the wing in to the airframe. As the wing is installed into the fuselage align the rear spar attach bolt hole with a spud bar. Install the rear spar attach bolts. Support the wing lower spar cap on the lower longeron with .50 inch* blocks under both wing spar caps. *(See step B-1)

# I ENGINEERING NUMBER SNOW ENGINEERING C0. WICHITA FALLS, TEXAS 

### REPORT 

# 0 4 r:a BV SERVICE LETTER #80GG DATE
*Revised to include 802A-0067 11/20/05 **Revised 12/21/05 REINSTALLING THE WINGS ON THE FUSELAGE (Con't): 3. Study the 20975 SHT 2 wing installation drawing. Maneuver the wing tips so that the main spars are aligned vertically and centered in the plane. Use the jacks or shims on the saw horses to provide the approximate dihedral angle.
4. Install the top and bottom splice blocks with only the inboard and outboard bolts. Grease the bolts and holes before installation. Snug the bolts, but do not torque them. DO NOT DRIVE BOLTS IN HOLES. Light tapping on the bolts with a small hammer is OK.
5. Install the wing attach angles per Step L. since the wings must be pulled apart to install the top bolts.
6. Position the fail safe plate and bolt it in place where possible. Install all the hardware according to drawing 20975 SHT 3. Remove the splice blocks and install the remaining fail safe plate hardware. Install the splice blocks and hardware according to drawing 20975 SHT 3. Install the 20618-1 plate according to drawing 20975 SHT 3. Do not forget to put the tube nut sleeves in as the tube nuts are installed. Torque all the bolts as called out on drawing 20975 SHT 3.
7. Inspect the installation of fail safe plate and splice blocks. Insp.
L. WING ATTACH ANGLE INSTALLATION:
1. Before starting the new wing attach angle installation, it is important to know that the wing is positioned vertically exactly in the same position as before it was removed. Refer to the measurements made in Step B-1 and install the correct thickness blocks under the spar caps.
2. New p/n: 20605-1 and p/n: 20745-1 wing attach angles are required after the spar structure has been changed.
3. To install the wing attach angles consult drawing 20975.Place a bullet nose 3/8" diameter punch in the fuselage wing attach bushings. Locate the wing attach angles as shown on drawing 20975SNOW ENGINEERING CO. 

### ENGINEERING "uMaER WICHITA FALLS, TEXAS REPORT #80GG ORDER X MODEL I TITLE 6Y CHN'D See B81

SERVICE LETTER #80GG Leland Snow SEflIAL DATE See Bel PAGE OF *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 WING ATTACH ANGLE INSTALLATION(Cont'd): SHT 3. Hold the attach angle in place and tap the punch to mark the angle. 4. Drill and ream the angles in a drill press as called out on drawing 20975. Clamp the steel p/n 20745-1 doubler angle inside the aluminum angle when drilling. Temporarily install the angles by bolting them to the frame. Use a.1285 bit to drill through the pilot holes in the main spar through the wing attach angles, holding the drill perpendicular to the face of the main spar. Check to see that the holes in the attach angles are in the correct position in regard to the angle radius and edge distance. S. Drill 23/64" through the pilot holes, holding the drill motor with the bit perpendicular to the face of the main spar. Ream the 8 holes in each spar with a.374 reamer. Mark the location of each attach angle and remove them to clean shavings and deburr. 6. Grease the bolts and the frame bushings in preparation for installation of the wing attach angles. Install the wing attach angles as shown on drawing 20975. It is necessary to pull the wings apart to install the top bolts that attach the angles to the fuselage tube. 

### fur WING INSTALLATION COMPLETION: 1. Check that the rear spar bolts are installed and properly torqued.
2. Clean the spar splice and attach angle area. Install putty around splice blocks as described in drawing 20993. INSPECT the installation to be sure a11 bolts are torqued and installed properly. Insp. 3. Install the fuel vent tube between the wings. Hook up the wiring harness that was removed. Hook up the pitot line and install the pitot tube and lift detector switch in the left wing.
4. Check the finger strainer in the fuel fitting and clean it as required. Install the fuel hose fitting and the drain valve withSNOW ENGINEERING CO. WICHITA FALLS, TEXAS

SERVICE LETTER #80GG 

### ENGINEERING NUMBER REPORT #80GG ORDER X MODEL BY CHK'D See Bel Leland Snow SERIAL DATE See Bel PAGE OF *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 WING INSTALLATION COMPLETION (Con't): Rector Seal in the bottom of the wing. Connect the fuel hose to the wing fitting.
5. Install and rig the flaps and ailerons as described in the Owners Manual Maintenance Section. Be sure to connect the aileron bellcrank to the aileron push pull tube in the fuselage. Check that the flight controls operate properly. Cycle the flaps and check for proper operation.
6. Install the wing tips, wing root fairing and as necessary any lighting and or other equipment that was removed.
7. Before the hopper is installed, you must have an inspector inspect the wing splice connection and wing attach angle installation.
8. INSPECT wing connection, attach angle installation, and items M-1 through M-6. Insp. 9. Install the hopper, gatebox and adaptor, windshield and instrument panel as described in the OWNERS MANUAL Maintenance Section.
10. Complete any other installations required.
N FINAL INSPECTION, FLIGHT TEST, AND FAA FORMS: l. With all fuselage skins removed, conduct INSPECTION of all installations required during wing removal and reinstallation. Make general airworthiness inspection of aircraft. Insp. 2. Install all fuselage skins. Must have OK to flight test. 3. OK to flight test Insp. DateSNOW ENGINEERING CO. 

### I ENGINEERING I """"BER 

# L WICHITA FALLS, TEXAS REPORT I... 

### ~ I ... __9

SERVICE LETTER #80GG DATE I1/5/05 1 17 *Revised to include 802A-0067 11/20/ **Revised 12/21/05 FINAL INSPECTION, FLIGHT TEST, AND FAA FORMS (Cont'd):
4. This is a major repair so complete the aircraft maintenance records and FAA Form 337 as instructed in FAR Part 43. Amend the weight and balance sheet to show the additional weight (37.0 lbs.) of the thicker upper and lower spar caps at station +19.75 for serial numbers 0001 through 0091, and for the additional weight (40.8 lbs) of the fail safe plate at station +21.1, if this plate was not already installed.
5. Flight test aircraft. Trim aircraft, check lift detector to activate stall horn 4 to 6 mph above stall speed, empty hopper and flaps UP. Note any squawk that should be addressed.
6. Flight test satisfactory. Pilot Date

0. EDDY CURRENT INSPECTION: Aircraft Total Time
1. Prior to scrapping the lower spar cap extension, eddy current inspect per PS197 all 10 holes in the outboard spar joint at WS 193 3/8. Report any cracks found to the factory.
2. Also eddy current inspect the outboard two holes in the lower main spar cap per PS197. Report any cracks found to the factory. Eddy current inspect 8 holes in each outboard spar joint: 

### sl Date Cracks No Cracks Eddy current inspect 2 outboard holes in each lower main spar cap: 

## I-M Date Cracks No Cracks If cracked, indicate size of crack, which area of hole crack was found, and which part or parts was found cracked. Crack Description:SNOW ENGINEERING CO. 

### ENGINEERING rUMBIR WICHITA FALLS, TEXAS REPORT 4 nRnpR X ODEL I TITLE SERVICE LETTER #80GG DATE .0 *Revised to include 802A-0067 11/20/05 **Revised 12/21/05 P. LIST OF DRAWINGS AND TOOLS REQUIRED: (*send with each kit) Drawings
20288 Sht 1,2 SK547 20380 Sht 1,2,3 SK551 Shts 1 thru 5 20975 Sht 2 SK604 20993 *Copy of S/L #80GG 20994 Sht 2 *Pull list for kit ordered 20631 Process Spec #101, #102 21107 Process Spec #181, #130

2485 Dia. (for 1/4 Dia. bolts) 374 Dia. (for 3/8 Dia. bolts)

LIST OF PARTS REQUIRED (1 ea.) p/n: 20975-55-500 spar change kit