Electrospark Deposition for the Repair of 

Army Main Battle Tank Components 

by Victor Champagne, Marc Pepi, and Brian Edwards 

ARL-TR-3849 July 2006 

Approved for public release; distribution is unlimited. 
NOTICES 

Disclaimers 

The findings in this report are not to be construed as an official Department of the Army position unless 

so designated by other authorized documents. 

Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of the 

use thereof. 

Destroy this report when it is no longer needed. Do not return it to the originator. 
Army Research Laboratory 

Aberdeen Proving Ground, MD 21005-5069 

ARL-TR-3849 July 2006 

Electrospark Deposition for the Repair of 

Army Main Battle Tank Components 

Victor Champagne, Marc Pepi, and Brian Edwards 

Weapons and Materials Research Directorate, ARL 

Approved for public release; distribution is unlimited.
ii

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering 

and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, 

including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson 

Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to 

comply with a collection of information if it does not display a currently valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 

1. REPORT DATE (DD-MM-YYYY)

July 2006 

2. REPORT TYPE 

Final 

3. DATES COVERED (From - To) 

March 2005–March 2006 

5a. CONTRACT NUMBER 

5b. GRANT NUMBER 

4. TITLE AND SUBTITLE 

Electrospark Deposition for the Repair of Army Main Battle Tank Components 

5c. PROGRAM ELEMENT NUMBER 

5d. PROJECT NUMBER 

EWU M159 

5e. TASK NUMBER 

6. AUTHOR(S) 

Victor Champagne, Marc Pepi, and Brian Edwards 

5f. WORK UNIT NUMBER 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

U.S. Army Research Laboratory 

ATTN: AMSRD-ARL-WM-MC 

Aberdeen Proving Ground, MD 21005-5069 

8. PERFORMING ORGANIZATION 

 REPORT NUMBER 

ARL-TR-3849 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) 

11. SPONSOR/MONITOR'S REPORT 

 NUMBER(S) 

12. DISTRIBUTION/AVAILABILITY STATEMENT 

Approved for public release; distribution is unlimited. 

13. SUPPLEMENTARY NOTES 

14. ABSTRACT 

This report discusses the successful application of electrospark deposition (ESD) to reclaim expensive U.S. Army main battle 

tank components which had no other means of being repaired. The components included the M1A1 main battle tank cradle 

(fabricated from AISI 4130 steel, then chrome plated) and the M1A1 helical (sun) gear shaft (chrome-plated AISI 9310). These 

parts had exhibited large corrosion pits and wear in service. Systems were dead-lined based on the discovery of these anomalies 

during inspection and the fact that insufficient replacement parts were available. There was no approved repair procedure for 

these components, and conventional weld repair technologies had been eliminated at Anniston Army Depot (ANAD), AL, to 

repair large pits. Approximately 8% of the vehicles overhauled at ANAD were defective, and deeply corroded parts were 

removed from the systems and put in storage. Emphasis of this report is placed upon the ESD process development and 

qualification. 

15. SUBJECT TERMS

welding repair, electrospark deposition, ESD, reclamation, ESTCP 

16. SECURITY CLASSIFICATION OF: 

19a. NAME OF RESPONSIBLE PERSON

Victor Champagne 

a. REPORT 

UNCLASSIFIED 

b. ABSTRACT 

UNCLASSIFIED

c. THIS PAGE 

UNCLASSIFIED

17. LIMITATION 

OF ABSTRACT 

UL 

18. NUMBER 

OF PAGES 

46 19b. TELEPHONE NUMBER (Include area code) 

410-306-0822 

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18
iii

Contents 

List of Figures v

List of Tables vi

1. Introduction 1

2. Components 1

3. ESD 2

4. Objective 6

5. Problem 6

6. Approach 7

6.1 Training ...........................................................................................................................7 

6.2 ESD Procedure Development (M1A1 Helical Gear Shaft).............................................8 

6.2 ESD Procedure Development (M1A1 Cannon Cradle) ................................................12 

6.3 Repair Qualification ......................................................................................................13 

6.3.1 Metallography .....................................................................................................13 

6.3.2 Hardness Testing .................................................................................................15 

6.4 Inspection Criteria .........................................................................................................15 

6.5 Engineering Approval ...................................................................................................17 

7. Discussion 18

8. Cost Analysis 20

9. Recommendations/Future Work 20

10. Conclusions 21

Appendix A. M1A1 Cradle Reclamation Procedure 23
iv

Appendix B. M1A1 Helical (Sun) Gear Reclamation Procedure 29

Distribution List 36 
v

List of Figures 

Figure 1. M1A1 main battle tank cannon cradle (arrow)................................................................2 

Figure 2. Cannon cradle disassembled from tank...........................................................................3 

Figure 3. Arrow indicates location of the helical gear shaft within the M1A1 main battle tank 

AGT-1500 engine. .....................................................................................................................3 

Figure 4. Schematic of the helical gear shaft and its relation to other engine components............4 

Figure 5. Photomacrograph of an M1A1 helical gear shaft (reduced 60%). ..................................4 

Figure 6. Equipment utilized for ESD repair of components. ........................................................5 

Figure 7. Photo showing ESD torch applying deposit on the inside diameter of a cradle with 

a rotating electrode.....................................................................................................................6 

Figure 8. An example of corrosion pits noted on a helical gear shaft (magnified 20×). ................7 

Figure 9. Test samples used for ESD process parameter optimization for the M1A1 helical 

gear shaft repair. Top block is chrome plated, and bottom block is uncoated AISI 9310 

steel (magnified 1.5×). ...............................................................................................................8 

Figure 10. The ESD parameters chosen for condition 4 were selected as optimal.........................9 

Figure 11. Optical macrograph showing two ESD-filled defects as well as one unfilled 

defect (magnified 2×)...............................................................................................................10 

Figure 12. SEM micrograph of the surface of condition 4 after ESD repair (magnified 22×).....10 

Figure 13. SEM micrograph of a section through condition 4 after ESD repair (magnified 

40×)..........................................................................................................................................11 

Figure 14. ESD being performed on an actual helical gear shaft containing defects at ARL. .....12 

Figure 15. Photomicrograph showing interface between deposit and substrate. Substrate was 

AISI 9310 steel etched with 2% nital (magnified 200×). ........................................................14 

Figure 16. Porosity around the ESD deposit (“halo effect”) of a chrome-plated sample 

(magnified 5×). ........................................................................................................................14 

Figure 17. Magnified view of figure 16 utilizing the differential interference contrast mode 

for optical viewing (magnified 50×)........................................................................................15 

Figure 18. Polished and etched cross section showing porosity associated with the “halo 

effect” in a chrome-plated 9310 steel sample. Etchant: 2% nital (magnified 500×). .............16 

Figure 19. Polished sample cross section of an ESD-filled, chrome-plated defect showing no 

anomalies (magnified 200×). ...................................................................................................16 

Figure 20. Plot of hardness through ESD into the base metal, showing similar hardness 

values. ......................................................................................................................................17 

Figure 21. Micrographs of Knoop microhardness indents through the ESD into the base 

metal. Base metal etched with 2% nital (magnified 50× [left] and 100× [right])...................18 
vi

Figure 22. Schematic of fatigue dog-bone specimen to be used to generate baseline data. .........19 

Figure 23. Schematic of defect dimensions to be machined into fatigue dog-bone specimens. 

These defects will be machined into one-half of the specimens, and subsequently filled 

with ESD..................................................................................................................................19 

List of Tables 

Table 1. ESD parameter optimization for M1A1 helical gear shaft. ..............................................9 

Table 2. ESD parameter optimization for M1A1 cannon cradle. .................................................12 

Table 3. Microhardness test results; Knoop scale; 500 gmf, 50× objective. ................................17 
1

1. Introduction 

This report describes the development of the electrospark deposition (ESD) repair for 

components from a U.S. Army main battle tank. This work was performed in support of the 

Environmental Security Technology Certification Program (ESTCP) FY02 project proposal 

titled “Electrospark Deposition as a Depot-Level Chromium Plating Replacement, Field-Level 

Brush Plating Replacement and In-Situ Repair Technology on Aircraft, Vehicle, and Ship 

Components.” The objectives of this project were as follows: (1) to demonstrate and validate 

ESD as a replacement for electrolytic hard chrome plating on complex, relatively small-area, 

line-of-sight applications for which high velocity oxy fuel is difficult or costly to utilize; (2) to 

demonstrate and validate ESD as a field repair technology to replace brush-plated chromium, 

cadmium, and nickel, and to repair other coatings (such as ion-vapor deposited aluminum) or 

base materials which have localized damage or defects; and (3) to utilize ESD for repair of 

damaged components for which there is no current repair procedure. 

The components chosen for the demonstration clearly satisfied objectives 2 and 3 and were 

selected for the significant cost savings. Previous to the implementation of ESD technology, 

each part had been inspected, removed from service, and put into storage because of corrosion 

pits and wear. The rejection rate became an important issue, since there was a shortage of 

available replacement parts. The success of this effort was realized through cost avoidance by 

reclaiming these parts. Each cradle costs ~$24,000 while a helical gear costs approximately 

$2,000. Although these repairs do not directly address an environmental issue, it can be 

demonstrated that these costs savings would not have been realized had this ESTCP effort not 

been undertaken. 

2. Components 

The two components utilized for ESD repair include the M1A1 cannon cradle and the M1A1 

helical (sun) gear shaft. A cannon cradle on an actual M1A1 tank is shown in figure 1, while 

figure 2 shows a cradle that has been removed from a tank. The helical gear shaft is shown in an 

actual cut-away section of an AGT-1500 engine (figure 3), while figure 4 shows a schematic of 

the gear and its relation to other engine components. Figure 5 shows an actual gear shaft which 

was shipped from Anniston Army Depot (ANAD) to the U.S. Army Research Laboratory (ARL) 

for this project. 
2

Figure 1. M1A1 main battle tank cannon cradle (arrow). 

3. ESD 

The equipment used for ESD is shown in figure 6 (taken from Price1). ESD is a pulsed-arc, 

microwelding process that uses short-duration, high-current electrical pulses to weld a 

consumable electrode material to a metallic substrate and is distinguished from other arc welding 

processes in that the spark duration is limited to a few microseconds and the spark frequency is 

1000 Hz or less. ESD offers a particular advantage when coating or repairing materials 

considered difficult to weld because of heat-affected-zone (HAZ) issues. Further, many materials 

can be processed without heat treatment before or after ESD. Components can be restored to 

original dimensions as the substrate material remains near to ambient temperature and thermal 

 1

Price, N. ASAP presentation, Global Leaders In Electrospark Deposition. Presented at the U.S. Army Research Laboratory, 

Aberdeen Proving Ground, MD, 25 October 2005. 
3

Figure 2. Cannon cradle disassembled from tank. 

Figure 3. Arrow indicates location of the helical gear shaft within the M1A1 main battle 

tank AGT-1500 engine. 
4

Figure 4. Schematic of the helical gear shaft and its relation to other engine components. 

Figure 5. Photomacrograph of an M1A1 helical gear shaft (reduced 60%). 
5

Figure 6. Equipment utilized for ESD repair of components.1

distortion; shrinkage and high residual stresses can be avoided.2 Figure 7 shows the application 

of an ESD deposit. This provides extremely rapid solidification, resulting in a nanocrystalline 

structure or, in some cases, an amorphous surface layer that is extremely dense, forming a 

metallurgical bond to the substrate. The low heat input eliminates deleterious thermal stresses or 

changes in metallurgical structure, otherwise known as the HAZ, allowing it to be considered for 

heat-sensitive applications. ESD can be used for applications requiring corrosion and wear 

resistance as well as the build up of worn or damaged areas on parts. ESD is also an 

environmentally friendly process, and the deposition of toxic materials can be accomplished with 

the use of a fume hood to capture any dangerous gases that may evolve. ESD operators require 

no specialized safety protection other than eyewear and a dust mask in some cases. The only 

major disadvantage is that the ESD electrode is relatively small (~0.125 inches in diameter), 

making the repair of large surface areas impractical and expensive. 

 2

http://www.twi.co.uk/j32k/unprotected/band_1/power_electro.html (accessed 6 March 2006). 
6

Figure 7. Photo showing ESD torch applying deposit on the inside 

diameter of a cradle with a rotating electrode. 

4. Objective 

The objective of this ESTCP effort was to implement the ESD process for repairing M1A1 

components under the Dem/Val in the ESTCP FY02 project proposal mentioned in section 1. 

5. Problem 

The M1A1 main battle tank components presented in this report were fabricated from alloy 

steels. After years of service, large corrosion pits (1/8 × 3/8 in and 0.060 in deep) and wear 

formed (figure 8). Systems were dead-lined based on surface anomalies discovered during 

inspection. Insufficient replacement parts were available. There was no approved repair 

procedure for these components, and conventional weld repair technologies had been eliminated 

at Anniston Army Depot (ANAD) to repair these large pits. Approximately 8% of the 

components overhauled at ANAD in 2003 were determined to be defective and were removed 

from the systems and put in storage. 
7

Figure 8. An example of corrosion pits noted on a helical gear shaft (magnified 20×). 

6. Approach 

The approach can be broken down into the following five major tasks: 

1. Training, 

2. ESD procedure development, 

3. Repair qualification, 

4. Inspection criteria, and 

5. Engineering approval. 

6.1 Training 

Initial ESD training was completed at ARL and was attended by repair personnel, technicians, 

engineers, and first-line supervisors representing ARL, ANAD, and representatives from several 

major aerospace companies. ARL was chosen as the site for the initial training because it had 
8

leveraged $31,000 of internal research and development funds to purchase an ESD unit and was 

the only Army research facility to have a fully operational system. In addition, ARL was the 

monitor of the Army efforts in ESD and also responsible for coatings characterization for the 

Army. A follow-up training session was conducted at ANAD specifically designed to address 

the subject component. As part of this study, coatings of Stellite 21, Inconel 718, and 

Inconel 625 were deposited onto low-alloy carbon steel and Inconel 718 substrates. 

6.2 ESD Procedure Development (M1A1 Helical Gear Shaft) 

The ESD repair procedure was developed and proved out at ARL for the gear shaft. Numerous 

ESD trials were conducted at ARL in order to determine the optimal set of process parameters 

that would result in a dense, adherent deposit. These trials were performed on coupons 

representing the material of the sun gear (chrome-plated AISI 9310 steel). Defects were 

machined into test samples (figure 9), and subsequently filled using ESD. Table 1 summarizes 

the iterative process utilized for each of the six defects, while figure 10 shows a representative 

scanning electron micrograph (SEM) of a section of each defect. Condition 4 was considered to 

exhibit the optimal coating characteristics and is highlighted in table 1. 

Figure 9. Test samples used for ESD process parameter optimization for 

the M1A1 helical gear shaft repair. Top block is chrome 

plated, and bottom block is uncoated AISI 9310 steel 

(magnified 1.5×). 
9

Table 1. ESD parameter optimization for M1A1 helical gear shaft. 

 Condition 1 Condition 2 Condition 3 Condition 4 Condition 5 Condition 6

Base material 9310 steel 9310 steel 9310 steel 9310 steel 9310 steel 9310 steel 

Non-ESD coating Chrome 

plating 

Chrome 

plating 

Chrome 

plating 

Chrome 

plating 

Chrome 

plating 

Chrome 

plating 

Electrode alloy Inconel 718 Inconel 718 Inconel 625 Inconel 718 Inconel 718 Inconel 718 

Electrode diameter (in) 0.125 0.125 0.125 .125 0.125 0.125 

Pulse rate (Hz) 400 400 400 400 400 400 

Capacitance (μF) 30 30 30 30 30 30 

Voltage (V) 140 200 140 140 150 120 

Step rate (Hz) 340 340 340 300 300 300 

Swing 4 4 4 4 4 4 

Rotate increment 4 4 4 4 4 4 

Direction CCW CCW CCW CCW CCW CCW 

Interval 8 8 8 8 8 8 

Shielding gas Argon Argon Argon Argon Argon Argon 

Shielding gas flow rate 

(CFH) 

35 35 35 35 35 35 

Note: CCW = counterclockwise, and CFH = cubic feet per hour. 

Condition 1 ESD Repair 

Micrograph. 

Condition 2 ESD Repair 

Micrograph. 

Condition 3 ESD Repair 

Micrograph. 

Condition 4 ESD Repair 

Micrograph. 

Condition 5 ESD Repair 

Micrograph. 

Condition 6 ESD Repair 

Micrograph. 

Figure 10. The ESD parameters chosen for condition 4 were selected as optimal. 
10

The parameters used in condition 4 were chosen to be used for the repair of the helical gear shaft. 

These parameters were chosen for the uniformity and density of the coating, the clean interface 

between the coating and substrate, and the lack of voids and intergranular sites. Figure 11 shows 

an optical macrograph of two ESD-filled defects, as well as an unfilled defect, while figure 12 

includes an SEM micrograph of the surface of condition 4. Figure 13 shows an SEM micrograph 

of a cross section of condition 4. 

ESD-repaired defects 

Unfilled defect 

Figure 11. Optical macrograph showing two ESD-filled defects as well as one 

unfilled defect (magnified 2×). 

Figure 12. SEM micrograph of the surface of condition 4 after ESD repair 

(magnified 22×).
11

Figure 13. SEM micrograph of a section through condition 4 after ESD repair (magnified 40×). 

The optimal ESD process parameters established through numerous iterations for the repairing of 

defects within the M1A1 helical gear shaft are those of condition 4: 

• Material AISI 9310 steel 

• Electrode: Inconel 718 

• ESD unit settings: 

 - Rotating torch 

 - Pulse rate = 400 Hz 

 - Capacitance = 30 μF 

 - Voltage = 140 V 

Once these parameters were established, defects on actual helical gear shafts were repaired 

utilizing ESD (figure 14). 
12

Figure 14. ESD being performed on an actual helical gear shaft containing defects at ARL. 

6.2 ESD Procedure Development (M1A1 Cannon Cradle) 

Determination of optimal parameters for the M1A1 cannon cradle repair was developed in a 

similar manner to the helical gear shaft. However, in this case, the ESD repair procedure was 

developed at ANAD and subsequently refined and proved out at ARL. Table 2 contains the 

iterations utilized. 

Table 2. ESD parameter optimization for M1A1 cannon cradle. 

 Condition 1 Condition 2 

Base material 4130 steel 4130 steel 

Non-ESD coating Chrome plating Chrome plating 

Electrode alloy Inconel 718 Inconel 718 

Electrode diameter (in) 0.125 0.125 

Pulse rate (Hz) 580 400 

Capacitance (μF) 20 30 

Voltage (V) 100 150 

Step rate (Hz) 270 340 

Swing 3 3 

Rotate increment 3 3 

Direction CW CW 

Interval 6 6 

Shielding gas Argon Argon 

Shielding gas flow rate (CFH) 35 35 

Note: CW = clockwise. 
13

The optimal ESD process parameters established for the repairing of defects within the M1A1 

cannon cradle were those of condition 2: 

• Material AISI 4130 steel 

• Electrode: Inconel 718 

• ESD unit settings: 

 - Rotating torch 

 - Pulse rate = 400 Hz 

 - Capacitance = 30 μF 

 - Voltage = 150 V 

6.3 Repair Qualification 

The repair qualification of the components was based upon the ability of the coating to adhere 

adequately to the substrate to withstand a finish grinding procedure. ARL conducted tests where 

mechanical pits were machined into AISI 4130 steel blocks, representative of the base material 

and subsequently filled utilizing the ESD repair procedure developed for the component. 

Additional samples that were chrome plated were also repaired by ESD and compared to the 

initial test group to determine the feasibility of performing an ESD repair on chrome-plated 

parts. A subsequent grinding operation was performed, after the pits were completely filled, to 

simulate subsequent manufacturing to bring the part back to the final dimension and surface 

finish requirement. Metallographic examination and hardness testing were performed on the 

samples and compared to the substrate. 

6.3.1 Metallography 

Metallography was utilized to examine test pieces that had defects filled with ESD to ensure that 

the deposit did not contain significant voids, porosity, or cavities. This would give an indication 

that the adhesion to the substrate material was adequate. Specimens were sectioned through the 

deposit and mounted in phenolic powder. The mounted specimens were subsequently rough 

polished using silicon carbide paper ranging in grit size from 240 to 2400. Final polishing was 

accomplished with 1-μm diamond followed by 0.05-μm alumina. For the most part, the 

interface between the substrate and the ESD deposit was determined to be acceptable (figure 15, 

representative); however, areas of surface porosity were sometimes encountered with the chrome 

plated samples (figures 16 and 17, representative). Advanced Surfaces and Processes (ASAP), 

Inc., describes this phenomenon as, “small defects (named the “halo effect”) where ESD meets 

the chrome.”3

 ASAP, Inc. indicated that improvements are seen in reducing/eliminating this 

effect specifically when the ESD equipment parameters were maintained at low energy while 

 3

Price, N. ESD/Chrome Halo Effect; Advanced Surfaces and Processes, Inc.: Cornelius, OR, 1 October 2004, p 1. 
14

ESD Deposit 

Substrate 

Figure 15. Photomicrograph showing interface between deposit and substrate. Substrate 

was AISI 9310 steel etched with 2% nital (magnified 200×). 

ESD deposit 

Actual helical gearshaft 

Figure 16. Porosity around the ESD deposit (“halo effect”) of a chrome-plated sample 

(magnified 5×). 
15

ESD deposit 

Figure 17. Magnified view of figure 16 utilizing the differential interference 

contrast mode for optical viewing (magnified 50×). 

applying the ESD/chrome interface. Figure 18 shows a polished cross section displaying the 

porosity associated with the “halo effect,” while figure 19 shows no anomalies for a different 

chrome-plated ESD deposit. 

6.3.2 Hardness Testing 

The Knoop microhardness scale (with a major load of 500 gmf) was utilized to assess the 

hardness of the deposit and the substrate, even though it has been shown that the ESD process 

has little to no deleterious effect on the substrate.4 The substrate was AISI 9310 steel heat 

treated to a hardness of ~40 HRC, as the results in table 3 show. The hardness of the deposit and 

the base metal was essentially the same. In addition, the hardness of the base metal was not 

altered as a result of the ESD process. Figure 20 shows a graph of the hardness data, and 

figure 21 includes a micrograph of the hardness indents through the deposit into the base metal. 

6.4 Inspection Criteria 

The methods of inspection employed for the repair of the cannon cradle reflect the concerns of 

serviceability (visual inspection), dimensional conformance, and surface finish, while an 

additional liquid penetrant inspection is required for the helical gear shaft. Stereoscopic 

inspection was performed utilizing a 10× lens to examine the repaired surface for evidence of 

blistering, peeling, and/or cracking, which is not allowed and is a cause for rejection. 

 4

Wang, P. Z.; Pan, G. S.; Zhou, Y.; Qu, J. X.; Shao, H. S. Accelerated Electrospark Deposition and Wear Behavior of 

Coatings. Journal of Materials Engineering and Performance 1997, 6 (6), 780–784. 
16

Figure 18. Polished and etched cross section showing porosity associated with the 

“halo effect” in a chrome-plated 9310 steel sample. Etchant: 2% nital 

(magnified 500×). 

Figure 19. Polished sample cross section of an ESD-filled, chrome-plated defect 

showing no anomalies (magnified 200×). 
17

Table 3. Microhardness test results; Knoop scale; 500 gmf, 50× objective. 

Reading Knoop 

Approx. 

HRC Reading Knoop 

Approx. 

HRC 

1 331.0 32.6 13 313.6 30.3 

2 326.1 32.0 14 372.4 37.2 

3 361.4 36.1 15 390.9 38.9 

4 390.9 38.9 16 377.3 37.7 

5 361.9 36.1 17 381.8 38.1 

6 365.0 36.5 18 395.0 39.3 

7 390.3 38.9 19 397.9 39.6 

8 364.5 36.4 20 395.0 39.3 

9 405.2 40.2 21 396.8 39.5 

10 405.8 40.3 22 392.6 39.1 

11 390.3 38.9 23 401.5 39.9 

12 391.5 39.0 24 397.9 39.6 

Hardness Traverse Through ESD Deposit

0

50

100

150

200

250

300

350

400

450

1.5

4.5

8.5

12.5

16.5

20.5

24.5

28.5

32.5

36.5

40.5

44.5

Depth from Surface (mils)

Knoop Measurement (H

K

Deposit Base Material

Interface 

40 HRC 

35 HRC 

Figure 20. Plot of hardness through ESD into the base metal, showing similar hardness values. 

6.5 Engineering Approval 

The reclamation procedure for the cannon cradle was approved by ANAD Engineering and has 

been performed since 25 June 2003. The procedure for the helical gear shaft awaits the results of 

testing ESD repaired test gears within the AGT-1500 engine test stand at 25 and 100 hr. 

Additional components have been selected for possible ESD repair based on the success of this 

effort, including the M88/M60 roadwheel arm spindle, the M198 recoil rod, and the M1A1 

converter shaft. 
18

Figure 21. Micrographs of Knoop microhardness indents through the ESD into the base metal. Base metal 

etched with 2% nital (magnified 50× [left] and 100× [right]). 

7. Discussion 

The compact ESD equipment is so relatively easy to operate that it could be incorporated for use 

on U.S. Navy ships such as aircraft carriers and submarines, as well as at U.S. Air Force repair 

facilities and Army depots that perform intermediate-level maintenance activities. Components 

that would normally have to be removed from the weapons system and shipped back to a depotlevel facility could be repaired on-site, eliminating costs and waste generation. There are also 

significant environmental benefits associated with the implementation of ESD technology 

including the elimination of brush and hard chromium plating and the wastes associated with its 

use. Fatigue testing should be performed for the qualification of loaded rotating components. 

Flat dog-bone fatigue specimens will be fabricated with and without ESD repair to produce 

baseline data. These specimens are schematically illustrated in figures 22 and 23. 

Since the approval of the ESD repair for the M1A1 cannon cradle by the Tank Automotive 

Command (TACOM), there have been 15 parts identified for reclamation. This equates to a 

potential cost savings of ~$360,000 to be realized by ANAD, based upon the rejection rates 

during the fourth quarter FY03 and the first half of FY04. A total of 189 parts was inspected, 

and 15 were identified for reclamation. To date, nine of these parts have been successfully 

repaired by ESD technology. 
19

Figure 22. Schematic of fatigue dog-bone specimen to be used to generate baseline data. 

Figure 23. Schematic of defect dimensions to be machined into fatigue dog-bone specimens. These 

defects will be machined into one-half of the specimens, and subsequently filled with 

ESD. 
20

8. Cost Analysis 

The following analysis calculates the cost savings to date by the implementation of the repair of 

the Army fighting vehicle component at ANAD for the nine M1A1 cannon cradles that have 

been repaired, as well as the anticipated cost savings for all 15 parts that have been identified for 

repair. The cost to purchase a new component is $24,636.00. The reclamation costs have been 

determined to be $698.50, based on a labor rate of $76.50/manhour for 9 hours and a material 

cost of $10.00. 

Using these facts, the cost savings for repairing nine components can be calculated as follows: 

• The cost to purchase nine new parts: $24,636.00 × 9 = $221,724.00. 

• The cost to repair nine pitted parts: $698.50 × 9 = $6,286.50. 

The total cost savings equals the cost to purchase nine new parts minus the cost to repair nine 

pitted parts or $221,724.00 – $6,286.50 = $215,437.50. 

The cost savings for repairing 15 parts can be calculated as follows: 

• The cost to purchase 15 new parts: $24,636.00 × 15 = $369,540. 

• The cost to repair 15 pitted parts: $698.50 × 15 = $10,477.50. 

The total cost savings equals the cost to purchase 15 new parts minus the cost to repair 15 pitted 

parts or $369,540 – $10,477.50 = $359,062.50. 

9. Recommendations/Future Work 

ARL purchased and installed an audible feedback force control tool developed by Pacific 

National Laboratories to be used in conjunction with the ESD process. The audible pressure 

sensing device is intended to provide the operator feedback related to his or her technique. ARL 

discussed this apparatus with ASAP at a 5 August 2005 meeting. This effort was funded in part 

through a Congressional Plus-Up Program managed by Phil Darcey of Benet Labs. 

Testing is underway at ASAP to evaluate the effectiveness of this instrument. The second 

system for ANAD has not been installed. ARL has not conducted a study to evaluate this 

system, but preliminary discussions revealed that the consensus is that it may be a good training 

tool in that it does prevent the operator from applying excess pressure but may be a hindrance to 

an experienced ESD operator. Regardless, at this time, the jury is still out since there is no 

quantifiable data available to make a sound decision. 
21

At the last meeting at ARL, ASAP presented the progress to date on the project “Feasibility of 

Electrospark deposition (ESD) on Carburized 9310 Steel.” The ultrasonic consolidation method 

to improve the density of the ESD deposit was discussed. Preliminary results indicate that the 

UT technique can not only improve the density of the ESD deposit but also increase the 

hardness. This is a result of the compressive stresses imparted by the UT method, which is 

analogous to peening the surface. The fatigue data that was generated for the ESTCP 

Electrospark Deposition Demonstration Plan was discussed, and plans were made to test 

10 fatigue specimens containing defects that are to be repaired by ESD and 10 fatigue samples 

without defects or ESD repair, as a baseline. 

10. Conclusions 

• ESD has been demonstrated to be a viable repair of corrosion pits and wear on both AISI 

4130 and 9310 steels for use on nonrotating components. 

• Caution must be taken when repairing chrome-plated components in order to 

reduce/eliminate the “halo effect.” 
22

INTENTIONALLY LEFT BLANK.
23

Appendix A. M1A1 Cradle Reclamation Procedure 
24

RECLAMATION PROCEDURE – M1A1 Cannon Cradle 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PMD 03-39 (REV 1) PAGE 1 OF 4 PAGE DATE: 25 June 2003 

NOUN: Cradle NSN: 1015-01-262-8613 P/N: 9377202 

UNIT PRICE: $24,636.00 

END ITEM: M1A1 ESTIMATED RECLAMATION COST: 

 MANHOURS: 9 @ $76.50 = $ 688.50

MATERIALS: = 10.00 

PREPARED BY: Ivey 

 TOTAL = $ 698.50 

REMARKS: Suggestion AMVA030051

PURPOSE: To repair pits in the 13.254”+ .003” ID of Cradle, P/N 9377202. 

The pits to be repaired are those that still remain after the cradle ID is 

ground the maximum amount allowed during the preparation phase of the ID 

chrome plating reclamation procedure found in DMWR 9-2350-264-2. 

 

NOTES: 

1. Disassembly, cleaning, and assembly to be IAW DMWR 9-2350-264-2. 

2. Cradle must meet all other requirements of DMWR 9-2350-264-2 prior to 

becoming a candidate for repair using this procedure. 

3. IMPORTANT-Repair only the pits that are in “Zone AR” and the .380” wide 

area of the ID between “Zone AR” and the end of the cradle (See Drawing 

9377202). Pits in “Zone AT” of the ID are not to be repaired using this 

procedure.

4. Pits larger than .375”Ø x .050” cannot be repaired using this 

procedure. 

5. No more than 10 pits may be repaired using this procedure. 

6. This procedure has been successfully accomplished at ANAD (See attached 

photos). 

1. EQUIPMENT: 

a. As required by DMWR 9-2350-264-2. 

b. ElectroSpark Deposition (ESD) Equipment as manufactured by Advanced 

Surfaces and Processes, Inc., or equal. http://www.advanced-surfaces.com/ 

c. Hand-held, high-speed grinder w/grinding tool and wire brush. 

d. ID Grinder. 

 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002)
25

RECLAMATION PROCEDURE – M1A1 Cannon Cradle 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PMD 03-39 (REV 1) PAGE 2 OF 4 PAGE DATE: 25 June 2003

2. MATERIAL: 

a. As required by DMWR 9-2350-264-2. 

b. Vapor degreaser. 

c. Inconel 718 bare electrode (.125” Diameter x 4” long). 

3. PROCEDURE: 

a. Clean cradle using vapor degreaser. 

b. Using hand-held grinder w/wire brush, remove corrosion from pit. 

c. Using hand-held grinder w/grinding tool, break the sharp edges of the 

pit. If possible, maintain a width to depth ratio of 10:1 minimum to 20:1. 

The finish on the excavated defect should be in the 32-64 rms range for 

best ESD results. 

d. All excavated areas and areas immediately adjacent to areas to be ESD 

repaired should be aggressively rubbed with a suitable medium grade 

abrasive pad followed by an isopropyl alcohol wash using a clean, lintfree cloth. If ESD repairs are not made within 24 hours after cleaning, 

it is recommended that the area to be ESD repaired be re-cleaned using the 

method described in this paragraph. 

e. Grounding: All components requiring ESD repair must be properly 

grounded. The grounding clamp should be placed on an area of the part not 

designated to receive ESD and must be tightly clamped to prevent arcing 

between the ground clamp and the component. Place ground clamp as close 

to ESD work zone as practicable. 

f. Electrode Selection and Installation: A .125” diameter electrode shall 

be used for this repair, of either composition listed in paragraph 2c. The 

electrode selected should be evaluated for straightness as excessive run 

out will cause poor ESD. Electrode tip shall resemble a rounded cone 

geometry (shaped using Dremel® or similar tool), and shall stick out from 

torch by approximately 1-inch. The process of reshaping and cleaning the 

electrode tip will be done extensively during the ESD repair process as 

the electrode is consumed. 

g. Cover Gas: Shielding the ESD area with a cover gas is recommended 

whenever possible. For this procedure, argon gas with a flow rate of 

35 CFH worked effectively. 

h. Electrode Rotational Speed and Stroke: An electrode rotation speed of 

approximately 1200 rpm is generally prescribed for affecting ESD repairs. 

The stroke utilized when repairing may include one or more of the 

following: 1) climbing only, 2) cutting only, 3) combination of cutting 

and climbing, 4) circular or semi-circular, and 5) zigzag. 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
26

RECLAMATION PROCEDURE – M1A1 Cannon Cradle 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PMD 03-39 (REV 1) PAGE 3 OF 4 PAGE DATE: 25 June 2003

i. Using the ESD Equipment with the rotating torch (ASAP Model AH-98-MKIDD), 

the following settings/parameters and the electrode listed in paragraph 

2c, fill the pit to .005” - .010” above the parent material surface. This 

will ensure complete cleanup during grinding. 

• Pulse Rate – 580 Hz 

• Capacitance – 20 mfd 

• Voltage – 100 volts 

• Shielding gas – Argon 

• Shielding gas flowrate – 35 SCFH 

j. Using ID grinder, grind ID to prepare for chroming IAW DMWR 9-2350-264-2. 

k. Chrome plate and finish grind ID IAW DMWR 9-2350-264-2. 

4. INSPECTION: 

Characteristic Method of Inspection Requisite

Serviceability Visually (10X Microscope) No blistering, 

 peeling, cracking 

 allowed. 

 

Dimensional Measure IAW DMWR 9-2350-264-2 

Surface Finish Measure IAW DMWR 9-2350-264-2 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
27

RECLAMATION PROCEDURE – M1A1 Cannon Cradle 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PMD 03-39 (REV 1) PAGE 4 OF 4 PAGE DATE: 25 June 2003

 

 PITS PREPARED FOR ESD REPAIR REPAIR PROCESS

 

 

AFTER ESD REPAIR, CHROME PLATING, AND FINISH GRINDING

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
28

INTENTIONALLY LEFT BLANK.
29

Appendix B. M1A1 Helical (Sun) Gear Reclamation Procedure 
30

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 1 OF 6 PAGES DATE: January 11, 2006

NOUN: helical gear NSN: P/N: 12284387 

UNIT PRICE: $2,195.00 

END ITEM: M1A1 ESTIMATED RECLAMATION COST: 

 MANHOURS: 8 @ $76.50 = $ 612.00

MATERIALS: = $ 30.00 

PREPARED BY: 

 TOTAL = $ 642.00 

REMARKS:

PURPOSE: To repair pits and wear marks which extend through the chrome 

plating to the base metal in the 3.5005”+ .0005” OD of helical gear shaft, 

P/N 12284387. 

 

NOTES: 

1. Disassembly, cleaning, and assembly to be IAW NMWR 9-2835-255-5. 

2. Gear shaft must meet all other requirements of NMWR 9-2835-255-5 prior 

to becoming a candidate for repair using this procedure. 

3. IMPORTANT- Repair only corrosion pits and wear marks that are in “Zone 

7” (See Drawing 12284387). Wear marks larger than 0.375” wide cannot be 

repaired using this procedure.

4. Pits larger than .375”Ø x .050” deep cannot be repaired using this 

procedure. Wear marks larger than .375” wide cannot be repaired using this 

procedure. 

5. No more than 3 flaws may be repaired using this procedure. 

6. This procedure has been successfully accomplished at ARL (See attached 

photos). 

1. EQUIPMENT: 

a. As required by NMWR 9-2835-255-5. 

b. ElectroSpark Deposition (ESD) Equipment as manufactured by Advanced 

Surfaces and Processes, Inc., or equal (http://www.advanced-surfaces.com/) 

c. Hand-held, high-speed grinder w/grinding tool and wire brush. 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
31

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 2 OF 6 PAGES DATE: January 11, 2006

2. MATERIAL: 

a. As required by NMWR 9-2835-255-5. 

b. Vapor degreaser. 

c. Inconel 718 bare electrode (.125” Diameter x 4” long). 

3. PROCEDURE: 

a. Machine the 3.500 to 3.501 inch diameter (NMWR 9-2835-255-5, Figure G-2) 

removing the existing chrome plating down to the base metal. 

b. Measure machined diameter. If diameter is 3.490 inches or more, gear 

shaft may be reclaimed. If diameter is less than 3.490 inches, discard 

gear shaft. 

c. Use steel shot (NMWR 9-2835-255-5, item 26, Appx. C) at a peening 

intensity of 8 to 10A with a minimum coverage of 150% and shot peen area 

to be sprayed IAW AMS-S-13165. Mask features not to be chrome plated. 

d. Clean gear shaft using vapor degreaser. 

e. Using hand-held Dremel® tool (or equivalent), remove corrosion from 

pit. 

f. Using hand-held Dremel® tool (or equivalent), break the sharp edges of 

the pit or wear mark. If possible, maintain a width to depth ratio of 

10:1 minimum to 20:1. The finish on the excavated defect should be in the 

32-64 rms range for best ESD results. 

g. All excavated areas and areas immediately adjacent to areas to be ESD 

repaired should be aggressively rubbed with a suitable medium grade 

abrasive pad followed by an isopropyl alcohol wash using a clean, lintfree cloth. If ESD repairs are not made within 24 hours after cleaning, 

it is recommended that the area to be ESD repaired be re-cleaned using the 

method described in this paragraph. 

h. Grounding: All components requiring ESD repair must be properly 

grounded. The grounding clamp should be placed on an area of the part not 

designated to receive ESD and must be tightly clamped to prevent arcing 

between the ground clamp and the component. Place ground clamp as close 

to ESD work zone as practicable. 

i. Electrode Selection and Installation: A .125” diameter electrode shall 

be used for this repair, of either composition listed in paragraph 2c. The 

electrode selected should be evaluated for straightness as excessive run 

out will cause poor ESD. Electrode tip shall resemble a rounded cone 

geometry (shaped using Dremmel® or similar tool), and shall stick out from 

torch by approximately 1-inch. The process of reshaping and cleaning the 

electrode tip will be done extensively during the ESD repair process as 

the electrode is consumed. 

j. Cover Gas: Shielding the ESD area with a cover gas is recommended 

whenever possible. For this procedure, argon gas with a flow rate of 

35 CFH worked effectively. 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
32

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 3 OF 6 PAGES DATE: January 11, 2006

k. Electrode Rotational Speed and Stroke: An electrode rotation speed of 

approximately 1200 rpm is generally prescribed for affecting ESD repairs. 

The stroke utilized when repairing may include one or more of the 

following: 1) climbing only, 2) cutting only, 3) combination of cutting 

and climbing, 4) circular or semi-circular, and 5) zigzag. 

l. Using the ESD Equipment with the rotating torch (ASAP Model AH-98-MKIDD), 

the following settings/parameters and the electrode listed in paragraph 

2c, fill the pit or wear mark to .005” - .010” above the parent material 

surface. This will ensure complete cleanup during grinding. 

• Pulse Rate – 400 Hz 

• Capacitance – 30 mfd 

• Voltage – 140 volts 

• Shielding gas – Argon 

• Shielding gas flowrate – 35 SCFH 

m. Finish grind OD IAW Eng. Dwg. 12284387. 

n. Chrome plate gear shaft diameter in accordance with NMWR 9-2835-255-5 

(Paragraph D.14, Appendix D) to exceed final diameter requirements shown 

on Figure G-2. Minimum chrome thickness must be 0.002 inch after final 

machining. 

o. Place plated gear shaft in oven (IAW NMWR 9-2835-255-5; Paragraph 2.1) 

heated to 265 ± 10oF for five (5) hours. Remove from oven. Machine chrome 

plated surface to meet dimensional and finish requirements shown in NMWR 

9-2835-255-5 (Figure G-2). Chrome thickness after final machining must be 

from 0.002 to 0.005 inch. 

p. Inspect gear shaft IAW NMWR 9-2835-255-5 (OIP-12284368/12284387, Table 

4-6). 

q. Inspect chrome plating IAW NMWR 9-2835-255-5 (Paragraph D.13, Appendix 

D). 

r. Balance gear shaft IAW NMWR 9-2835-255-5 (Appendix L). 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
33

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 4 OF 6 PAGES DATE: January 11, 2006

4. INSPECTION: 

Characteristic Method of Inspection Requisite

Serviceability Visually (10X Microscope) No blistering, 

 peeling, or cracking 

 allowed. 

 Liquid Penetrant Inspection IAW Eng. Dwg. 12284387

 

 

Dimensional Measure IAW Eng. Dwg. 12284387 

Surface Finish Measure IAW Eng. Dwg. 12284387 

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002)
34

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 5 OF 6 PAGES DATE: January 11, 2006

 CORROSION PIT FOR ESD REPAIR WEAR MARK FOR ESD REPAIR

 

 CORROSION PIT PREPARED FOR ESD CORROSION PIT FILLED IN BY ESD

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002) 
35

RECLAMATION PROCEDURE – M1A1 Helical (Sun) Gear shaft 

ANNISTON ARMY DEPOT 

PROCESS MANAGEMENT DIVISION 

NUMBER: PAGE 6 OF 6 PAGES DATE: January 11, 2006

CORROSION PIT AFTER ESD REPAIR AND FINISH GRINDING

SIOAN FORM 750-127-E, Rev 12 Mar 97 

(RPLS SDSAN Form 1002)
NO. OF 

COPIES ORGANIZATION 

36

 1 DEFENSE TECHNICAL 

 (PDF INFORMATION CTR 

 ONLY) DTIC OCA 

 8725 JOHN J KINGMAN RD 

 STE 0944 

 FORT BELVOIR VA 22060-6218 

 1 US ARMY RSRCH DEV & 

 ENGRG CMD 

 SYSTEMS OF SYSTEMS 

 INTEGRATION 

 AMSRD SS T 

 6000 6TH ST STE 100 

 FORT BELVOIR VA 22060-5608 

 1 INST FOR ADVNCD TCHNLGY 

 THE UNIV OF TEXAS 

 AT AUSTIN 

 3925 W BRAKER LN 

 AUSTIN TX 78759-5316 

 1 DIRECTOR 

 US ARMY RESEARCH LAB 

 IMNE ALC IMS 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

 3 DIRECTOR 

 US ARMY RESEARCH LAB 

 AMSRD ARL CI OK TL 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

ABERDEEN PROVING GROUND

 1 DIR USARL 

 AMSRD ARL CI OK TP (BLDG 4600) 
NO. OF NO. OF 

COPIES ORGANIZATION COPIES ORGANIZATION

37

 1 USA RDECOM 

 AMSRD AMR AE F M 

 K BHANSALI 

 BLDG 4488 RM B276 

 REDSTONE ARSENAL AL 35898 

 1 NAVAL RSRCH LAB 

 ENVIRON TECHNLGY PM 

 B D SARTWELL 

 CODE 6170 

 4555 OVERLOOK AVE SW 

 WASHINGTON DC 20375 

 1 USA RDECOM 

 AMSRD AMR AE F M 

 G WECHSLER 

 BLDG 4488 RM B269 

 REDSTONE ARSENAL AL 35898 

 1 USA RDECOM 

 AMSRD AMR AE F M 

 M KANE 

 BLDG 4488 RM B266 

 REDSTONE ARSENAL AL 35898 

 1 USA RDECOM 

 AMSRD AMR AE F M 

 R MCFARLAND 

 BLDG 4488 RM B272 

 REDSTONE ARSENAL AL 35898 

 1 USA RDECOM 

 AMSRD AMR AE F M 

 L D CRISP 

 BLDG 4488 RM B274 

 REDSTONE ARSENAL AL 35898 

 1 US ARMY AVN AND MIS CMD 

 AMSAM EN 

 M FEATHERS 

 BLDG 111 

 REDSTONE ARSENAL AL 35898 

 1 CMD AMCOM 

 AMCOM G 4 LOGISTICS 

 AMSAM EN EV 

 W ALVAREZ 

 REDSTONE ARSENAL AL 35898-5000 

 1 NAVAL RSRCH LAB 

 CTR FOR CORROSION SCI 

 AND ENGRG 

 B BAYLES 

 CODE 6132 BLDG 3 RM 264 

 4555 OVERLOOK AVE SW 

 WASHINGTON DC 20375-5342 

 1 NAVAIR 

 J YADON 

 CODE 4.9 NADEP 

 JACKSONVILLE FL 32212 

 1 NAVAL AIR DEPOT 

 MTRL ENGRG DIV 

 G BARNETT 

 AIR 4.9.7 

 CHERRY POINT NC 28533 

 1 NAVAIR 

 W FRAZIER 

 AIR 4.9T 

 48066 SHAW RD 

 BLDG 2187 RM 1282 

 PATUXENT RIVER MD 20670 

 1 NAVAIR 

 J BARONOWSKI 

 CODE 497600D 

 1900 N KNOX RD STOP 6213 

 CHINA LAKE CA 93555 
38

INTENTIONALLY LEFT BLANK.