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 C1 ~ 

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 edge 
SNOW 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: 

,2 

6] 69 

60 

62 

~ 26 63 

26 60 

u az 

U . /i~✓ \ •' 

~ 2] 

0

25 

~ 

~ 24 

'•:• .

~ 

/ 

16 

56 
SNOW ENGINEERING CO. 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 [7NUMBER

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 the 
SNOW ENGINEERING CO. I ENGINEERING [7NUMBER

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 20975 
SNOW 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 with 
SNOW 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. Date 
SNOW ENGINEERING CO. I ENGINEERING I """"BER 

WICHITA FALLS, TEXAS REPORT I...~I L ... __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