## ENGINEEI2ING NUMIII?R SNOW ENGINEERING CO. WICHITA FALLS,TEXAS 

### REPORT
SERVICE LETTER #245 nrcns

SUBJECT: Split Sleeve Co1d Expansion of Lower Spar Cap Holes - Rework of ln-service Aircraft in the 8-hole Configuration MODELS: AT-802, AT-802A S/N 802-0092 through 802-0178 REFERENCE: (1) - Fatigue Technology Inc. Process Specification 8101D (2) - Snow Engineering Co. Drawing 20995, sheet 1
C.F.NF.RAT, • This Service Letter provides a set of detailed instructions for cold 

### working the 2 outboard-most wing center splice block holes in the lower spar cap. This document addresses airplanes in the 8 hole block configuration. For clarification, the splice block bolt holes are numbered from inboard to outboard. The inboard-most hole is defined as the "#1 Hole" and the outboard-most hole is defined as the "#8 Ho1e". See Figure 1 below. The terms "#8 Hole" and "#7 Hole" will be used throughout this document to identify holes being cold worked.



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# n #2 ~ 

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Figure 1- 8 Hole Block Numbering Scheme



### CAUTION: A MIS-DRILLED OR MIS-REAMED HOLE WILL RUIN THE SPAR CAP. THERE IS NO FIX FOR AN OVERSIZED OR EGG-SHAPED HOLE. OVERSIZED OR EGG-SHAPED HOLES WILL REQUIRE SPAR CAP REPLACEMENT. REPLACING A DAMAGED SPAR CAP CAN LEAD TO SIGNIFICANT COST AND SIGNIFICANT AIRCRAFT DOWNTIME. EXERCISE EXTREME CAUTION AND GOOD AVIATION MAINTENANCE PRACTICES AND TECHNIQUE WHEN PERFORMING THE STEPS IN THIS SERVICE LETTER.

## ENGINEEItING """"""` SNOW ENGINEERING CO. WICHITn F,u.LS,'rsxns REPORT (1RT1F.R X ma

~ >iti. 

### SERVICE LETTER #245 nnre

EQUIPMENT: 

### The tools required to accomplish this rework are separated into 3 different tool kits and are color coded for ease of identification. The "Ye11ow" Tool Kit A is used when cold working the "4k8 Holes". The "Blue" Too1 Kit B is used when cold working the "#7 Holes". The "Red" Tool Kit C contains all other general tools used for this process. The instructions in this document specify that each hole size be worked separately. This is not only to eliminate opportunities for tool selection errors, but also to hold the spar cap stackup in place during the cold working process. While working from the "Yellow" tool kit, the "B1ue" tool kit should be closed, latched, and out of reach. While working from the "Blue" tool kit, the "Yellow" tool kit should be closed, latched, and out of reach.

P/N DESCRIPTION CASR-62-1 Starting Reamer (Ref .379 Dia.) CAG-62 Combination Gage CAMG-62 Mandrel Gage CAS-62-36F Flared Sleeve (2 ea.) CAM-62-2-60-V2 Mandrel MEN-26B-1223F Nosecap Assembly CAR-62-1-.4062 IGage Finish Reamer raple 1-'1'001 xat A^Ye11Ow TOO1 Kit° - 13/32 Sinished Holes (STDN = 62)

P/N DESCRIPTION CASD-80-1-C Starting Dri11 (Ref .453 Dia) CASR-80-1 Starting Reamer (Ref .470 Dia.) CAG-80 Combination Gage CAMG-80 Mandrel Gage CAS-80-40F Flared Sleeve (2 ea.) CAM-80-2-60-V2 Mandrel MEN-26B-1601F Nosecap Assembly CAR-80-1-.5000 Gage Finish Reamer raple L

- '1'001 nit 1s "i6171e '1'ool Kit" - 112 r - lnisnea Holes (STDN = 80)

P/N DESCRIPTION MB-30 Medium Brute Pu11er Unit FT-20 Power Pak PS200-1 120 microinch surface finish comparator plate SK398-1 Cold Work Tooling Fixture (See SK398-1 for

complete list of parts) 'i•anle 6-'POOl xat c'

~ aea Toot xit- - General ToolsSNOW ENGINEERING CO. "



# I ENGINEERING 

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"°"""` WICHITA FALLS, TEXAS 

### REPORT 

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SERVICE LETTER #245 unrr> 4/25/05 PERSONNEL QUALIFICATION: In order to perform the steps in this Service Letter, personnel must: a.) possess the tooling specified in the "Equipment" section of this document. b.) be trained and certified for eddy current inspection. c.) attend an Air Tractor sponsored training course and receive a certificate of completion for the Split Sleeve Cold Expansion process. This requirement may also be fulfilled by attending a Fatigue Technology Inc. training session and receiving a 

### Certificate of Training after the completion of that training. PROCEDURE: SECTION A- CLEAN AND GAIN ACCESS TO REPAIR AREA B. 1. Before accomplishing this Service Letter, thoroughly clean the

airplane, especially the hopper, gatebox, and wing splice area. B. 2. Gain access to the repair area as follows:

B. 2.1. Remove hopper dump push rod mechanism B. 2.2. Remove spray pump to spray valve tube B. 2.3. Remove bottom load fill tube B. 2.4. Remove spray pump supply tube B. 2.5. Remove gatebox fairing B. 2.6. Remove gatebox B. 2.7. Remove fiberglass enclosure skin SECTION 8- REMOVE HARDWARE, INSPECT #7 AND #8 HOLES B. 1. Shore aircraft wings as follows:

B. 1.1. Place wing jacks at wing tie-down ring locations. B. 1.2. Simultaneously raise both jacks until jack pads "just

contact" the tie-down ring on both left and right wings. B. 1.3. Simultaneously raise both jacks an additional 11/16 + 1/16

to unload the bolts in the lower cap splice connection and facilitate bolt removal. B. 2. Identify the spar lower cap "#7 and #8 hole" bolt locations. See

Figure 1. B. 3. Remove nuts from the two 3/8 bolts, both left and right side, in the

lower wing spar splice using good aviation maintenance practice. Use 1/4" aluminum pin punch to CAREFULLY tap bolts up and out of lower spar cap and splice blocks. NOTE: USE EXTREME CAUTION NOT TO SCRATCH INSIDE OF HOLES WITH PUNCH. B. 4. Remove nuts from the two 7/16 bolts, both left and right side, in

the lower wing spar splice using good aviation maintenance practice.SNOW ENGINEERING CO. 

## ENGINEERING """"""` WICHITA PA1.I.S, TEXAS REPORT C1R11RR x monit. 

### SERVICE LETTER #245 DKIII
Use 1/4" aluminum pin punch to CAREFULLY tap bolts up and out of lower spar cap and splice blocks. NOTE: USE EXTREME CAUTION NOT TO SCRATCH INSIDE OF HOLES WITli PUNCH. B. 5. Clean #7 and #8 holes using solvent and a soft bristle brush or rag.

Use compressed air to remove all solvent residue from the holes. B. 6. Eddy Current inspect 47 and #8 Holes" per Air Tractor PS 197. 

### IA

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### iIZoIC7H7

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### .1 `Y W IF BOTH #7 HOLES AND BOTH #8 HOLES PASS THE EDDY CURRENT INSPEC7'ION IN PS 197, PROCEED WITH THE STEPS IN THIS SERVICE LETTER. IF ANY HOLES FAIL THE EDDY CURRENT INSPECTION IN PS 197, DISCONTINUE THIS SERVICE LETTER.

SECTION C- COLD WORK #7 AND #8 HOLES C. 1. Install and locate SK398-1 attach block Tooling Fixture (See SK398):

C. I.I. Remove the two #3 5/8" dia. bolts from the center splice.

Install the tooling fixture with two 5/8" dia. studs, nuts, and washers as shown on SK398. Tighten the stud nuts. C. 1.2. Install drill press onto the drill press mounting plate.

Do not tighten 2 mounting bolts. C. 1.3. Lock Tapered Alignment Pin into drill chuck. C. 1.4. Position drill press so alignment pin slips into ho1e. C. 1.5. With Tapered Pin still in hole, tighten 2 mounting bolts. C. 1.6. Withdraw drill chuck from hole and remove alignment pin. C. 1.7. Dri1l fixture is now aligned with hole.
COLD WORK "#8 HOLE" TO 13/32 (STANDARD TOOL DIAMETER NUMBER, STDN = 62) Note: Accomplish the following Cold Work steps concurrently for both the left hand and right hand '48 Holes". C. 2. Acquire "Yellow" Tool Kit A and inventory for proper tools using

Table 1. C. 3. Ream the "#8 Hole" using the CASR-62-1 starting reamer. Sulfur based

cutting oil should be used for starting hole ream and all subsequent ream steps. After reaming, move SK398-1 Tooling Fixture out of the way and clean the hole with solvent and dry with compressed air. See Figure 2.SNOW ENGINEERING CO. WICHITA FALLS, TEXAS


### SERVICE LETTER #245 

## ENGINEERING """"""` REPORT

_ ORDER X ntOD 1 ' 1)Y CHK9) 

### Leland Snow mme 

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Starting Reamer 

### Figure 2 C. 4. The starting hole diameter must be .379 -.382. Check the starting

hole using the CAG-62 Go-No Go Combination Gage, or a ba11 gage and micrometer. When using the Go-No Go Combination Gage, a gage that can only be inserted to the first machined "step" identifies a properly reamed hole. The starting hole should be checked for ovality by inserting the gage a second time, rotated 90 ° . See Figure 3.

O O



# ~ Accept



## ~ Figure 3 Reject

C. 5. Select the CAM-62-2-60-V2 mandrel and inspect using the CAMG-62 GoNo Go gage or a micrometer. The mandrel major diameter shall be .3692 -.3702. The mandrel shall be checked at the beginning of each aircraft job because the mandrel diameter is critical for proper cold expansion of the hole. An excessively worn mandrel will pass through the CAMG-62 Go-No Go gage and shall be replaced. If the mandrel fails the diameter check, contact Air Tractor Customer Service Department for a replacement mandrel. See Figure 4.



# ~ Mandrel Check Fixture O 

# Accept Rejectand Discard Mandrel 

### FiQure 4 C. 6. Clean the hole using solvent and a soft bristle brush or rag. Use

compressed air to remove all solvent residue from the holes.

### SNOW ENGINEERING CO. 

## ENGINEERING """"""` WICHITA FALLS, TEXAS 

## REPORT (1RT1RR % mour.i.
SERVICE LETTER #245 nnrc
C. 7. Cold expand the hole. See Figure 5: C. 7.1. Select the CAS-62-32F split sleeve and slide it over the

mandrel. orient sleeve so that the split is pointing along the spar cap centerline facing inboard and the flared end is toward the Puller nosecap. C. 7.2. Insert the mandrel and sleeve into the starting hole.

Ensure sleeve orientation is correct per step 13.1 above. The sleeve should protrude from the topside of the hole 1/32",or more. C. 7.3. Place nosecap firmly against and perpendicular to the lower

surface of the splice block. C. 7.4. Activate Puller. Continue holding the trigger until

mandrel is through the entire lower spar cap stackup. Release trigger when the mandrel is clear of the structure. C. 7.5. Remove sleeve from the cold worked hole and discard.

Sleeves are used only once. 

### 0 0

SPLIT FACES INBOARD

C. 8. Check the cold expanded hole diameter using the CAG-62 Go-No Go Combination gage. The gage will fit into a properly expanded hole. The cold worked hole should measure .3840 as a minimum before the finish ream process. If the Go-No Go Combination gage will not fitSNOW ENGINEERING CO. WICHITA FALLS,TEXAS


### SERVICE LETTER #245 

## ENGINEERING N"A 101 " REPORT ORDER X nwula. IIV <:IIA'n 

### Leland .

C Jnow yi'I""i ' unT:


### into the hole, check for proper tool selection, check mandrel for proper diameter, then follow step 13 a second t

- ime. NoL

- e that a surface upset is created during the cold working process at each hole face. This surface upset is normal. See Figure 6.



# ~ ~ 

# ~ Go-No-Go Gage

0 a Combination Gage —\
NN Gage Finish Reamer Gage Finish Reamer 

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NN NN or Hole has been cold expanded,

NN KN or Hole has not been cold expanded. 

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Fieure 6

C. 9. Follow the Tooling Fixture alignment procedure previously described. C. 10. Finish ream the cold worked hole using the CAR-62-1-.4062 gage finish reamer. Finish reamed final hole must have a surface roughness of 120 microinches or smoother measured with surface finish comparator plates. See Figure 7.

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### Finish Reamer


### Figure 7 C. 11. Inspect finished hole. Finish reamed final hole must have a

diameter of .4058 +-002 /-.000 and must have a surface roughness of

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SNOW ENGINEERING CO. 

## ENGINEERING 

## ^ WICHITA FAi.7.s, TEXAS 

### REPORT I 1
SERVICE LETTER #245 un n:
120 microinches or smoother measured with surface finish comparator plates. Holes may be inspected using a ball gauge and micrometer, or air gauge with the proper calibrated hole standards. C. 12. Install new hardware in accordance with Drawing 20995, sheet 1.

SECTION 3- REMOVE RARDWARE, INSPECT, COLD A)ORK 47 HOLE" TO 1/2 HOLE (STANDARD TOOL DIAMETER NOMIDER, STDN = 80) C. 13. Acquire "Blue" Tool Kit B and inventory for proper tools using Table

2. C. 14. Identify the spar lower cap "#7 Hole" bolt locat

- ions. See Figure 1. C. 15. Remove clamp bolts at #6 hole locations. C. 16. Clean holes using solvent and a soft bristle brush or rag. Use

compressed air to remove all solvent residue from the holes. C. 17. Follow the Tooling Fixture alignment procedure previously described. C. 18. Drill the entire stackup of upper and lower blocks and lower cap at

the "#7 Hole" location using CASD-80-1-C starting drill. Sulfur based cutting oil should be used for starting hole drill and all subsequent ream steps. C. 19. Ream the "#7 Hole" using the CASR-80-1 starting reamer. After reaming, move SK398-1 Tooling Fixture out of the way and clean the hole with solvent and dry with compressed air. See Figure 8.

Starting Drill

Starting Reamer 

## Figure 8

C. 20. The starting hole diameter must be .470 -.473. Check the starting hole using the CAG-80 Go-No Go Combination Gage, or a ball gage and micrometer. When using the Go-No Go Combination Gage, a gage that can only be inserted to the first machined "step" identifies a properly reamed hole. The starting hole should be checked for ovality by inserting the gage a second time, rotated 90 0 . See Figure 9.SNOW ENGINEERING CO. WICHITA FALLS,TEXAS 

## ENGINEERING I """'" REPORT n
SERVICE LETTER #245 DA'115

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# ~ Accept _ Reject -



# ~ Figure 9
C. 21. Select the CAM-80-2-60-V2 mandrel and inspect using the CAMG-80 GoNo Go gage or a micrometer. The mandrel major diameter shall be ..4643-4653. The mandrel shall be checked at the beginning of each aircraft job because the mandrel diameter is critical for proper cold expansion of the hole. An excessively worn mandrel will pass through the CAMG-80 Go-No Go gage and shall be replaced. If the mandrel fails the diameter check, contact Air Tractor Customer Service Department for a replacement mandrel. See Figure 10.



# ~ Mandrel Check Fixture a 

# ~ )0
Accept Reject and Discard Mandrel 

### Figure 10

C. 22. Clean the hole using solvent and a soft bristle brush or rag. Use

compressed air to remove all solvent residue from the holes.

C. 23. Cold expand the hole. See Figure 11:

C. 23.1. Select the CAS-80-36F split sleeve and slide it over the

mandrel. Orient sleeve so that the split is pointing along

### SNOW ENGINEERING CO. 

## ENGINEERING NIIMIII11l WtCHrrn P,va.s, TexnS 

### REPORT x # 2 4 5 ORDER Moulal. rrrce nv cnnIo 

### See BelOW

SERVICE LETTER #245 

### Leland Snow sl"`In'. nn•n; rn<a: or 4/25/05 

### 1n 12 the spar cap centerline facing inboard and the end is toward the Pu11er nosecap. C. 23.2. Znsert the mandrel and sleeve into the starting hole.

Ensure sleeve orientation per step 29.1 above. The sleeve should protrude from the topside of the hole 1/32" or more. C. 23.3. Place nosecap firmly against and perpendicular to the lower

surface of the splice block. C. 23.4. Activate Puller. Continue holding the trigger until

mandrel is through the entire lower spar cap stackup. Release trigger when mandrel is clear of the structure. C. 23.5. Remove sleeve from the cold worked hole and discard.

Sleeves are used only once.



### SPLIT FACES INBOARD



### Figure 11 C. 24. Check the cold expanded hole diameter using the CAG-80 Go-No Go Combination gage. The gage will fit into a properly expanded hole. The cold worked hole should measure .4780 as a minimum 

### before the finish ream process. If the Go-No Go Combination gage will not fit into the hole, check for proper tool selection, check mandrel for proper diameter, then follow step 30 a second time. Note that aSNOW ENGINEERING CO. 

## ENGINEERING NUMnNR WICHITA FALLs, TEXAs 

### REPORT # 2 4 5 ORDER x M°n"'• TrrLE nv r•nn'n 

### See Below

SERVICE LETTER #245 Leland Snow "`"'"'' nnTc rncaa oV 

### 4/25/05 17 12 surface upset is created during the cold working process at each hole face. This surface upset is normal. See Figure 12.

Combination Gage 

# ~
NN Gage Finish Reamer- 

# ~ fzzq NN NN or 0 Go-No-Go Gage



# ~ 0
~ Gage Finish Reamer
Hole has been cold expanded.

or Hole has not been cold expanded.


### Fieure 12
C. 25. Follow the Tooling Fixture alignment procedure previously described. C. 26. Finish ream cold worked hole using CAR-80-1-.5000 gage finish

reamer. Finish reamed final hole must have a surface roughness of 120 microinches or smoother measured with surface finish comparator plates. See Figure 13.

0 0



### Finish Reamer


### Figure 13

C. 27. Inspect finished hole. Finish reamed final hole must have a

diameter of .4995 +.002 /-.000 and must have a surface roughness of 120 microinches or smoother measured with surfacefinish comparatorSNOW ENGINEERING CO. 

# I ENGINEERING NIIMIIISIt WICHITA FALLS, TEXAS 

## REPORT 

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SERVICE LETTER #245 

### nn•re 5 

### plates. Holes may be inspected using a ball gauge and micrometer, or air gauge with the proper calibrated hole standards. C. 28. Install new hardware in accordance with Drawing 20995, sheet 1.
SECTION 4- REASSEMSLE AIRPLANE AND RETIIRN TO SERVICE C. 29. Reinstall gatebox and all equipment removed in accordance with Airplane Owners Manual. C. 30. Make the following maintenance log entry in aircraft logbook:

"This aircraft, Air Tractor (model number)-(s/n), has been reworked in accordance with Snow Engineering Co. Service Let

- ter #245 and is approved for return to service, this date (date), signed (signature), (certificate and number).