NO. 

 

DATE 

PAGE

 DATE 

 

ALERT SERVICE BULLETIN 

A Subsidiary of Textron Inc.

AN APPROPRIATE ENTRY SHOULD BE MADE IN THE AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT 

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER

407-08-84 

Aug. 18, 2008 

1 of 26 

MODEL AFFECTED: 407

SUBJECT: TAILBOOM ASSEMBLY 407-030-801-201, 407-

030-801-203 AND 407-030-801-205, NEW

INSPECTION REQUIREMENTS. 

HELICOPTERS AFFECTED: All model 407 helicopters with one of the subject 

tailbooms installed.

 

COMPLIANCE: PART I Immediately after receipt of this bulletin. 

PART II At the next tailboom scheduled inspection 

and after every 300 flight-hours thereafter. 

PART III Within 25 flight-hours or 30 days after 

accomplishment of Part I. This inspection will affect 

tailbooms which have accumulated 6900 flight-hours 

or more, tailbooms with unknown total flight-hours or 

tailbooms reaching 6900 flight-hours in service. 

PART IV Within 25 flight-hours or 30 days after 

accomplishment of Part I. This inspection will affect 

tailbooms which have accumulated 8600 flight-hours 

or more, tailbooms with unknown total flight-hours or 

tailbooms reaching 8600 flight-hours in service. 

DESCRIPTION: 

Bell Helicopter Textron (BHT) has accomplished a thorough analysis of subject 

tailbooms which are built with chem-milled skins. This analysis has revealed that 

areas with high stress concentration could exist on the subject tailboom. BHT has not 

received any field report indicating a cracked skin in service on subject tailbooms. 

However, in the interest of safety, BHT has elected to introduce a new inspection 

schedule to subject tailboom assemblies. 
ASB 407-08-84 

Page 2 of 26 

PART I of this Alert Service Bulletin requires identification of the affected tailboom. 

PART II of this bulletin provides the new 300-hour recurring inspection details for all 

subject tailbooms.

 

PART III of this bulletin provides additional inspection details for subject tailbooms 

which have accumulated 6900 flight-hours or more or with total flight-hours 

unknown. Operators have the option to meet the requirement of PART III with a 10X 

magnifying glass inspection (Option “A”) performed every 150 flight-hours thereafter or 

by an Eddy Current inspection method (Option “B”) performed at every 500-hours 

interval. 

PART IV of this bulletin provides additional inspection details for subject tailbooms 

which have accumulated 8600 flight-hours or more or with total flight-hours 

unknown. Operators have the option to meet the requirement of PART IV with a 10X 

magnifying glass inspection (Option “A”) performed by maintenance personnel every 

50 flight-hours thereafter or a visual check (Option “B”) performed daily by the pilot as 

part of his daily preflight check. 

PART V of this bulletin provides the Instructions for Continued Airworthiness. 

APPROVAL: 

The engineering design aspects of this bulletin are TCCA approved. 

MANPOWER:

PART I: Approximately 0.25 man-hour is required to accomplish PART I of this 

bulletin. 

PART II: Approximately 2.5 man-hours are required to accomplish PART II of this 

bulletin. 

PART III: Approximately 0.50 man-hour is required to accomplish PART III of this 

bulletin when done under Option “A” (10X magnifying glass inspection method) or 1.0 

man-hour when done under Option “B” (Eddy Current inspection method). 

PART IV: Approximately 0.25 man-hour is required to accomplish PART IV, Option 

“A” of this bulletin. There is no impact when Option “B” is selected and done as part of 

the pilot’s daily preflight check. 

NOTE: Man-hours are based on hands-on time, and may vary with personnel and 

facilities available. 
ASB 407-08-84 

Page 3 of 26 

WARRANTY: 

There is no warranty associated with this bulletin. 

MATERIAL: 

Required Material: 

None required. 

Consumable Material: 

For PART II, PART III and PART IV: 

 Aircraft soap (C-318) under MIL-C-87936, as required. 

SPECIAL TOOLS: 

For Part III, Option “B”(when selected): Eddy Current inspection equipment as 

described in paragraph 3.0 of Appendix “A”. 

WEIGHT AND BALANCE: 

Not affected 

ELECTRICAL LOAD DATA: 

Not affected 

REFERENCES: 

ASB 407-07-80 

BHT-206-SRM-1 

BHT-407-MM-1, Rev 24, Maintenance Manual, Chapter 4 

BHT-407-MM-5, Rev 18, Maintenance Manual, Chapter 53 

Corrosion Control Guide, Chapter 10 

BHT-ALL-SPM, Rev. 2, dated 16 February, 2007 

PUBLICATIONS AFFECTED: 

BHT-407-MM-1, Rev 24, Maintenance Manual, Chapter 4 
ASB 407-08-84 

Page 4 of 26 

ACCOMPLISHMENT INSTRUCTIONS: 

PART I: Verification of affected tailboom: 

1. Upon receipt of this bulletin, verify the helicopter technical records to determine if 

you have tailboom assembly part number 407-030-801-201, 407-030-801-203 or 

407-030-801-205 installed on your helicopter. You can also physically confirm the 

tailboom Part Number by removing the aft driveshaft cover (Ref. Chapter 53 of the 

maintenance manual) and looking at the identification plate located near Boom 

Station (BS) 129 as shown in Figure 1. 

2. If identification as per Step 1 indicates that your tailboom is P/N 407-030-801-107, 

407-530-014-101 or 407-530-014-103, refer to Chapter 4 of your maintenance 

manual for the inspection schedule applicable to those tailboom assemblies. 

Annotate the helicopter technical records to indicate that your tailboom is not 

affected by this bulletin. 

 

3. If identification as per Step 1 above indicates that you have one of the subject 

tailboom assemblies, verify tailboom historical record sheet to determine total 

flight-hours of your tailboom. 

-NOTEIf the total flight-hours of your tailboom is unknown, it will be 

considered to have accumulated beyond 8600 flight-hours 

and the requirements described under PART II, PART III

and PART IV will apply 

4. Once the total time in service is known; 

a) For all subject tailbooms, regardless of their total time in service, accomplish 

inspection of your tailboom assembly as defined under PART II of this bulletin 

at the next scheduled inspection and every 300 flight-hours thereafter. 

b) If your tailboom assembly has accumulated 6900 flight-hours or more or if the 

total time is unknown, incorporate into the inspection schedule of subject 

tailbooms defined under PART II, one of the additional inspections as defined 

under PART III within the next 25 flight-hours in service or 30 days, whichever 

occurs first and repeat at applicable interval shown. 

c) If your tailboom assembly has accumulated more than 8600 flight-hours or if 

the total flight-hours is unknown, incorporate into the inspection schedule of 

subject tailbooms defined under PART II and PART III, one of the additional 
ASB 407-08-84 

Page 5 of 26 

inspections as defined under PART IV within 25 flight-hours or 30 days, 

whichever occurs first and repeat at applicable interval shown. 

5. Annotate your technical records to indicate at which time PART I of this bulletin 

was carried out. 

PART II Inspection requirements at each 300-hour interval for all subject 

tailbooms:

1. Gain access to the areas to be inspected by removing both driveshaft covers and 

both gearbox fairings halves from your tailboom assembly. Refer to BHT-407-MM5, Chapter 53. 

2. Clean the complete tailboom assembly (including the horizontal stabilizer, the two 

auxiliary finlets and the vertical fin) with aircraft soap (C-318) prepared in 

accordance with manufacturer’s recommendations to remove all traces of dirt, 

stains, exhaust residues and oil. 

3. (Ref. Figure 2) Examine the complete tailboom assembly following every 300 flighthours of operation for general condition, loose rivets, cracks or any other type of 

damage. Pay close attention to Areas “B”, “C”, “D”, “H” and “I” at the left side of 

the tailboom as indicated in Figure 2. 

4. Inspect for loose rivets in region shown in Figure 2, Area “A” and especially at 

those shown in Details “E”, “F”, “G”, and in Areas “C”, “D”, “H” and “I”. If a loose 

rivet or fastener is found, remove it per standard practices and inspect edges of 

hole for cracks using a 10X magnifying glass. If no crack is found, install correct 

diameter rivet or fastener (Ref. BHT-206-SRM-1, section 3). 

5. If no loose rivets or fasteners are found, use a 10X magnifying glass and examine 

tailboom skin at edge of bearing hanger supports and around fasteners shown in 

Figure 2, Details “E”, “F”, “G”, and Areas “H” and “I”. 

6. On left side of tailboom, use a 10X magnifying glass and examine tailboom skin 

just above edge of mating stabilizer upper attachment support as shown in Figure 

2, Areas “C” and ”D”. 

7. If no crack is found, annotate the helicopter technical records to indicate that PART 

II of this bulletin is complied with and return the tailboom to flight status. 

8. Repeat this inspection after every 300 flight-hours thereafter. When your tailboom 

reaches 6900 and 8600 flight-hours of service, add respectively to this inspection 

schedule, the applicable recurring inspection requirements as defined under 

PART III and PART IV of this bulletin. 
ASB 407-08-84 

Page 6 of 26 

9. If any crack is found in Step 3 through Step 6 above, replace the tailboom with a 

serviceable unit prior to next flight and notify Bell Helicopter Product Support 

Engineering department; 

a) If another affected tailboom is installed on the helicopter, determine the total 

time in service of that tailboom and apply appropriate inspection program as 

defined in this bulletin. 

b) If the total flight-hours of your tailboom is unknown, accomplish inspection 

requirements described under PART II, PART III and PART IV before putting 

this tailboom in service and repeat at intervals shown or selected until directed 

otherwise by BHT. 

10. If corrosion is found, refer to Chapter 53 of your maintenance manual for negligible 

damage limits or contact Product Support Engineering with details for assistance. 

PART III Additional inspection requirements for tailbooms with 6900 flighthours or more or with time unknown:

For tailbooms which have reached or exceeded 6900 flight-hours in service or with 

time unknown, in addition to PART II, incorporate to the inspection schedule, one of 

the following recurring inspections and repeat at the applicable interval shown; 

Option “A” (10X Magnifying glass 150-hour recurring inspection): 

-NOTEIt is permissible to transfer from one inspection program to 

the other for maintenance scheduling convenience (ex: 

Option “A” to Option “B). However, the inspection as 

described in the new program must be accomplished prior to 

next flight. Make an entry in the helicopter records to show 

that you have transferred from one inspection option to the 

other for traceability. 

-NOTEThe following inspection must be repeated at a maximum of 

150 flight-hours of time in service. However, the aft 

driveshaft cover section from the tailboom assembly must be 

removed to gain proper access to the area to be inspected. 
ASB 407-08-84 

Page 7 of 26 

1. Remove the aft driveshaft cover section in accordance with Chapter 53 of the 

maintenance manual. 

2. Use a clean cloth moistened with aircraft soap (C-318) prepared in accordance 

with manufacturer’s recommendations, as required, to remove any exhaust 

residues or dirt from areas to inspect, as shown in Figure 2, Areas “H” and “I”. 

3. On left side of tailboom, make sure that the tailboom skin is clean and that 

adequate lighting exists. Use a 10X magnifying glass and examine tailboom 

around fasteners shown in Figure 2, Areas “H” and “I”. 

4. If a crack is found, replace the tailboom with a serviceable unit prior to next flight 

and notify Bell Helicopter Product Support Engineering department; 

a) If another affected tailboom is installed on the helicopter, determine the total 

time in service of that tailboom and apply appropriate inspection program as 

defined in this bulletin. 

b) If the total flight-hours of your tailboom is unknown, accomplish inspection 

requirements described under PART II, PART III and PART IV before putting 

this tailboom in service and repeat at intervals shown or selected until directed 

otherwise by BHT. 

5. If no crack is found, the intent of PART III is complete. 

6. Make an entry in the helicopter records to show that PART III, Option “A” of this 

bulletin is completed. 

7. Repeat this inspection after every 150 flight-hours thereafter. 

8. When your tailboom reaches 8600 flight-hours, one of the additional recurring 

inspection requirements defined under PART IV must apply. 

Option “B” (Eddy Current 500-hour recurring inspection); 

-NOTEIt is permissible to transfer from one inspection program to 

the other for maintenance scheduling convenience (ex: 

Option “B” to Option “A). However, the inspection as 

described in the new program must be accomplished prior to 

next flight. Make an entry in the helicopter records to show 

that you have transferred from one inspection option to the 

other for traceability. 
ASB 407-08-84 

Page 8 of 26 

-NOTEThe following inspection must be repeated at a maximum of 

500 flight-hours of time in service. However, the aft 

driveshaft cover section from the tailboom assembly must be 

removed to gain proper access to the area to be inspected. 

1. Remove the aft driveshaft cover section in accordance with Chapter 53 of the 

maintenance manual. 

2. Use a clean cloth moistened with aircraft soap (C-318) prepared in accordance 

with manufacturer’s recommendations, as required, to remove any exhaust 

residues or dirt from areas to inspect, as shown in Figure 2, Areas “H” and “I”. 

3. Refer to Appendix “A” to set and calibrate the Eddy Current inspection equipment. 

4. On left side of tailboom, make sure that the tailboom skin is clean and inspect 

tailboom skin around fasteners heads in the shaded areas shown in Figure 2, 

Areas “H” and “I”. 

5. If a crack is detected, replace the tailboom with a serviceable unit prior to next 

flight and notify Bell Helicopter Product Support Engineering department; 

a) If another affected tailboom is installed on the helicopter, determine the total 

time in service of that tailboom and apply appropriate inspection program as 

defined in this bulletin. 

b) If the total flight-hours of your tailboom is unknown, accomplish inspection 

requirements described under PART II, PART III and PART IV before putting 

this tailboom in service and repeat at intervals shown or selected until directed 

otherwise by BHT. 

6. If no crack is found, the intent of PART III is complete. 

7. Make an entry in the helicopter records to show that PART III, Option “B” of this 

bulletin is completed. 

8. Repeat this inspection after every 500 flight-hours thereafter. 

9. When your tailboom reaches 8600 flight-hours, one of the additional recurring 

inspection requirements defined under PART IV must apply. 
ASB 407-08-84 

Page 9 of 26 

PART IV Additional inspection requirements for tailbooms with 8600 flighthours or more or with time unknown:

For tailbooms which have reached or exceeded 8600 flight-hours or with total flighthours unknown, in addition to PART II and PART III, incorporate to the inspection 

schedule, one of the following recurring inspections and repeat at the applicable 

interval shown; 

Option “A” (10X Magnifying glass 50-Hour recurring inspection): 

-NOTEIt is permissible to transfer from one inspection program to 

the other for maintenance scheduling convenience (ex: 

Option “A” to Option “B). However, the inspection as 

described in the new program must be accomplished prior to 

next flight. Make an entry in the helicopter records to show 

that you have transferred from one inspection option to the 

other for traceability. 

1. Use a clean cloth moistened with aircraft soap (C-318) prepared in accordance 

with manufacturer’s recommendations, as required, to remove any exhaust 

residues or dirt from both Areas “C” and “D” to look at, as shown in Figure 2. 

2. On left side of tailboom, make sure that the tailboom skin is clean and that 

adequate lighting exists. Use a 10X magnifying glass and examine tailboom 

around fasteners and just above the edge of upper stabilizer support as shown in 

Figure 2, Areas “C” and ”D”. 

3. If a crack is found, replace the tailboom with a serviceable unit prior to next flight 

and notify Bell Helicopter Product Support Engineering department; 

a) If another affected tailboom is installed on the helicopter, determine the total 

time in service of that tailboom and apply appropriate inspection program as 

defined in this bulletin. 

b) If the total flight-time of your tailboom is unknown, accomplish inspection 

requirements described under PART II, PART III and PART IV before putting 

this tailboom in service and repeat at intervals shown or selected until directed 

otherwise by BHT. 

4. If no crack is found, the intent of PART IV is complete. 

5. Make an entry in the helicopter records to show that PART IV, Option “A” of this 

bulletin is completed. 
ASB 407-08-84 

Page 10 of 26 

6. Repeat this inspection after every 50 flight-hours thereafter. 

Option “B” (Daily recurring check): 

-NOTEThis inspection can be performed by the pilot as part of his 

preflight check with paint/primer still present at the affected 

areas. 

-NOTEIt is permissible to transfer from one inspection program to 

the other for maintenance scheduling convenience (ex: 

Option “B” to Option “A). However, the inspection as 

described in the new program must be accomplished prior to 

next flight. Make an entry in the helicopter records to show 

that you have transferred from one inspection option to the 

other for traceability. 

1. Use a clean cloth moistened with aircraft soap (C-318) prepared in accordance 

with manufacturer’s recommendations, as required, to remove any exhaust 

residues or dirt from both Areas “C” and “D” to look at, as shown in Figure 2. 

2. On left side of tailboom, make sure that the tailboom skin is clean and that 

adequate lighting exists. Examine tailboom around fasteners and just above the 

edge of upper stabilizer support in the shaded areas shown in Figure 2, Areas “C” 

and “D”. 

3. If a crack is found, replace the tailboom with a serviceable unit prior to next flight 

and notify Bell Helicopter Product Support Engineering department; 

a) If another affected tailboom is installed on the helicopter, determine the total 

time in service of that tailboom and apply appropriate inspection program as 

defined in this bulletin. 

b) If the total flight-time of your tailboom is unknown, accomplish inspection 

requirements described under PART II, PART III and PART IV before putting 

this tailboom in service and repeat at intervals shown or selected until directed 

otherwise by BHT. 

4. If no crack is found, the intent of PART IV is complete. 

5. Make an entry in the helicopter records to show that PART IV, Option “B” of this 

bulletin is completed. 
ASB 407-08-84 

Page 11 of 26 

6. Repeat this inspection before first flight of each day thereafter. 

PART V Instructions for Continued Airworthiness

1. Maintain your tailboom in accordance with your 407 Maintenance Manual BHT407-MM-1 and the BHT corrosion control guide CSSD-PSE-87-001. 

2. Inspect your tailboom as per applicable requirements and recurring intervals as 

described herein. 
ASB 407-08-84 

Page 12 of 26 

Figure 1. Location of identification plate, tailbooms 407-030-801-201, 407-

030-801-203 or 407-030-801-205. 
ASB 407-08-84 

Page 13 of 26 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 1 of 6). 
ASB 407-08-84 

Page 14 of 26 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 2). 
ASB 407-08-84 

Page 15 of 26 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 3). 
ASB 407-08-84 

Page 16 of 26 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 4). 
ASB 407-08-84 

Page 17 of 26 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 5). 
ASB 407-08-84 

Page 18 of 26 

LEGEND: 

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030-

801-203 and 407-030-801-205 (Sheet 6). 
ASB 407-08-84 

Page 19 of 26 

APPENDIX “A”

1.0 Scope 

1.1 This procedure is provided to allow for the detection of 0.050” crack(s) 

emanating from beneath rivet heads. 

1.2 It is intended to provide as close as practical detection of cracks oriented in 

both the vertical and horizontal positions. 

2.0 Personnel Requirements 

2.1 Personnel performing inspection to this procedure shall be qualified Level II or 

III per the requirements of NAS 410 or equivalent, OR have successfully 

completed the BHT CTA NDE Field Maintenance course. The individual shall 

be certified as a Level I Special in Eddy Current per employer’s written practice 

for personnel training and certification. 

3.0 Equipment 

3.1 NDI Instrument: Hocking Phasec 2 Eddy current flaw detector or equivalent. 

3.2 Probe: Absolute pencil probe (50-500 kHz). 

3.3 BNC cable. 

3.4 BNC cable adapter. 

3.5 Teflon tape (C-460). 

3.6 Reference standard: Aluminum 3 Notch Crack Standard (P/N 29A029). 

4.0 Calibration 

4.1 Non-painted surface 

4.1.1 Connect cable and probe to the Phasec 2, power ON. 

4.1.2 Place a piece of Teflon tape onto the coil of the probe to decrease 

wearing of the probe and reduce chance of scratching the material under 

inspection. 

4.1.3 Press the MENU button to enter the setup mode. 

4.1.4 Setup instrument per Table 1. 

4.1.5 Press the MENU button to exit the setup mode. 

4.1.6 Place the pencil probe onto a good area of the standard away from any 

edge or crack and press the “BALANCE (load)” button as shown in Figure 

3. 

4.1.7 Lift the probe off the standard and adjust the PHASE as necessary so that 

the trace line (lift-off signal) moves from the center of the display to the 

left and exits the screen horizontally as shown in Figure 4. Re-BALANCE

with probe on the standard when complete. 

4.1.8 Sweep the probe over the 0.020” reference crack on the standard and 

verify signal response. 

4.1.9 Adjust coarse GAIN values if necessary to increase or decrease crack 

response amplitude. Figure 5 illustrates typical response from 0.020” flaw 

(approximately one grid division). 
ASB 407-08-84 

Page 20 of 26 

4.2 Painted surface 

4.2.1 Perform steps 4.1.1 through 4.1.5. 

4.2.2 BALANCE probe adjacent to the inspection area, then place probe on the 

reference standard (see Figure 7). 

4.2.3 The displayed balance point should appear to right of the previous 

balance (null) point (see Figure 6). 

4.2.4 Place one layer of notebook paper (~ 3-4 mils thick) over the calibration 

standard, and place the probe on top of the paper. The balance point 

should move left toward the center of the screen. Perform this step 

adding additional layers of paper until the balance point returns to center. 

This step will determine the approximate paint thickness in the area of 

inspection and allow the operator to compensate for any reduction of 

sensitivity due to the additional lift-off. 

4.2.5 With the determined number of notebook paper on top of the 

standard, Balance the Eddy current probe, and complete steps 

4.1.7 through 4.1.9. 

NOTE: Any type of paper may be used when compensating for paint 

thickness. The main consideration is that the paper (or any other 

material, i.e. plastic shim, tape, etc.) is electrically non-conductive. 

5.0 Pre-Inspection 

5.1 Ensure surfaces are clean and free of any loose debris, so as not to interfere 

with the inspection. 

6.0 Inspection 

6.1 Place the probe in intimate contact with the rivet area(s) to be inspected and 

Re-adjust the PHASE, if necessary, so that lift-off is horizontal from center null 

point to left. 

6.2 Scan the area of interest circumferentially (see Figure 7) while monitoring the 

display for a sudden increase in signal amplitude from crack-like indications. 

7.0 Evaluation 

7.1 Repeat calibration and rescan any areas where there is a vertical crack-like 

deflection. 

7.2 If indication persists, mark the location on the part. 

8.0 Accept/Reject Criteria

8.1 Any repeatable crack-like indication detected by the Eddy Current method 

shall be cause for rejection. 
ASB 407-08-84 

Page 21 of 26 

Gain 30.0/ 40.0 

X dB 30.0 

Y dB 40.0 

Phase 201.0 

FREQ. 200.0 

HIPASS DC 

LOPASS Hz 100.0 

BAND LOCK OFF 

PROBE 

Absolute

LOAD Uh 120 

INPUT GAIN High 

RECALL Setup 

SAVE Trace 

TRACE RECORD --- 

OFF 

ALARM SHAPE Off 

TOP ---- 

BOTTOM ---- 

LEFT ---- 

RIGHT ---- 

START ANGLE ---- 

END ANGLE ---- 

INNER ---- 

OUTER ---- 

STRETCH 50 ms 

ALARM ACTION None 

DISPLAY Spot 

SWEEP 5.0 s 

PERSIST 0.2 s 

GRATICULE Grid 1 

SPOT X 50% 

SPOT Y 50% 

MODE Normal 

PROBE I D 

Unknown 

POWER DOWN ---- 

Off 

KEY CLICK Off 

CONTRAST A/R 

VIDEO MODE --- 

Normal 

LANGUAGE --- 

English 

BAUD 9600 

TIME A/R 

DAY A/R 

MONTH A/R 

YEAR A/R 

 

 Table 1 
ASB 407-08-84 

Page 22 of 26 

FIGURE 3 
ASB 407-08-84 

Page 23 of 26 

FIGURE 4 
ASB 407-08-84 

Page 24 of 26 

FIGURE 5 
ASB 407-08-84 

Page 25 of 26 

FIGURE 6 
ASB 407-08-84 

Page 26 of 26 

FIGURE 7