United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9711210027

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301 South Church St., Suite 100 / P.O.  Box 1928 / Rocky Mount, NC 27802-

1928 / Telephone: (919) 977-2720 / Fax (919) 446-3830


Date:          September 23, 1997

Company:       Office of Nuclear Reactor Regulation

Fax Number:    301-415-1887

Attention:     Vern Hodge

Reference:     Report #10CFR21-0073

From:          Michael Nuding

Page:          1 of 9

Dear Sir:

Following this cover is a copy or our report 10CFR21-0076 for a 10CFR21

reportable defect with EMD air start motors.  This report supercedes our

interim report 10CFR21-0076-IR dated July 14, 1997.

A copy of this report is also being mailed to you.  We will begin our

notification to affected users tomorrow.

Should you have questions, please let us know:



Michael Nuding,

Quality Manager

                     Quality Performance With Pride

Section 4

Fig.4-3 "Typical Air Starting System Diagram" omitted.


The air starting sytem requires very little maintenance other than

cleaning and lubrication.

The air line lubricator is the only component of the system which

requires maintenance at intervals specified in the Scheduled Maintenance

Program.  Oil level in the bowl should be checked and the needle valves

should he adjusted for an oil flow rate of three drops per minute.  This

can be checked visually through the sight glass in the front of the


If oil does not flow, remove top plug and drip gland.  Clean parts and

passages, using kerosene, and blow out with compressed air.

Replace any defective gaskets or packing.  Reassemble, tightening drip

gland firmly, but carefully.

Compounded oils containing graphites, soap, or filters should not be used

in the lubricator.

Refer to applicable Engine Maintenance Manual for maintenance data on

starting motors and unattached accessories.

                                                  Report No. 10CFR21-0076

                                                        SEPTEMBER 22,1997



COMPONENT:     EMD Air Start Motors #40047506 & #40047507

SYSTEM:        Standby diesel generators with EMD diesel engines

CONCLUSION:    Defect is reportable in accordance with 10CFR21.

PREPARED BY:                            DATE:

               Donald D.  Galeazzi

               Engineering Manager

REVIEWED BY:                            DATE:

               Michael Nuding

               Quality Assurance Manager

                                             REPORT NO. 10CFR21-0076

                                             PAGE: 1 OF 5


This report supersedes our interim report 10CFR21-0076-IR dated July 14,


Engine Systems, Inc.  (ESI) received notification on 5/14/97 from

Commonwealth Edison, Quad Cities nuclear plant about an increase in

starter pinion abutments after installing the "new" style air motors.

ESI began an investigation of this issue through coordination with EMD

and Ingersoll-Rand (I-R), the starter manufacturer.

I-R discontinued production of the their model 89 air motor and

recommended their model 88 as a replacement.  The"new"style (#40047506 &

#40047507) air motors (I-R model 88) were then issued by EMD as

replacements for the "Old" style (#8367694 & #8377435 respectively) air

motors (I-R model 89).  #40047506 & #8367694 are for use on left hand

(standard) rotation engines (counter-clockwise while looking at engine

flywheel) and are applicable for most EMD diesel generators.  Right hand

rotation engines use #40047507 & #8377435 and are only applicable for

tandem diesel generator sets.  Left hand rotation and right hand rotation

air start motors are identical in design except some components are

reversed or are manufactured as mirror images to enable opposite


The EMD design pipes the two air motor pinion lines in series before

going to the main air valve "activate" input.  The intent of this design

is to pre-engage the pinion gear (achieve mesh between the pinion gear

and the engine ring gear) before starting air is supplied to the motor to

begin engine rotation (see Exhibit 1).

EMD has recently performed starting motor tests at their facility with I-

R using both "old" and "new" style air motors.  The results show that the

"old" style air motor is not a pre-engagement type (although, I-R thought

it was) and therefore it allows air motor rotation during pinion

abutment.  The testing also demonstrated that that the "new" style

starter is a positive engagement type and therefore it prevents motor

rotation during pinion abutment.  Under most starting scenarios, the

pinion gear will properly mesh with the engine ring gear, the engine

begins to crank and starts as normal.  The pinion gear has chamfered

teeth which allows the two gears to mesh easily, therefore, gear abutment

is rare.  If gear abutment does happen, the following will occur:

1. "Old" style starters:

     This motor is not a pre-engagement type; therefore, the pinion gear

     and engine ring gear "roll into" mesh as the air motor begins to

     rotate.  The engine cranks and starts normally.

     Rolling into mesh is not a problem for most applications because of

     the main air valve design.  From 1969 - present, EMD used a Graham-

     White (Salem) main air valve (EMD #8393335).  This valve uses a 2

     stage principle which allows a small amount of air to flow through

     the valve before the valve fully opens to deliver the main charge of

     air to the starting motors.  This provides a smooth deliverance of

     air to the air motors and eliminates a "shock" of air.  This also

     enables the air motors to rotate slowly for a very brief period of

     time before the main charge air is delivered to the air motors;

     thus, the pinion gear rotates slowly and meshes with the engine ring

     gear before full starting torque is applied by the motor.  Prior to

     this 2 stage valve, a Grove Flexflo main air valve was used.  This

     valve was not slow opening and gear damage could occur because full

     starting torque is applied during "roll in".

                                             REPORT NO. 10CFR21-0076

                                             PAGE: 2 OF 5

2.  "New" style starters:

     This motor is a pre-engagement type; therefore, engine rotation is

     prevented because the pinion has not traveled a sufficient distance

     to release an activate air signal to the main air valve.  The engine

     fails to start.

EMD feels that the pre-engagement operation of the current design "new"

style starter decreases engine starting reliability and therefore is not

acceptable for use on the EMD engine.  The "old" style starter has

demonstrated many years of reliable engine starting on the EMD diesel

engine and its continued use is recommended.  I-R is investigating

reinstatement of the "old" style starter for exclusive use by EMD.  They

are also looking at modifying the "new" style starter so that it performs

identically to the "old" style.


EMD #40047506       I-R #150BMPD88R543335    For left hand (standard)

                                             rotation engine.

EMD #40047507       I-R #150BMPD88L543336    For right hand (reverse)

                                             rotation engine.


Commonwealth Edison, Quad Cities is the only ESI customer to report this

type of problem.  According to Quad Cities, Savannah River also

experienced increased pinion abutment after installing the "new" style

air motor (motors not supplied by ESI).  These two installations are

somewhat unique because they do not have redundant banks of air Start

motors and they do not have pinion recycle circuitry.  Most EMD nuclear

safety related diesel generators have both of these features.  Units with

redundant banks of starting motors and recycle circuitry are less likely

to notice a change in starting reliability after installing the "new"

style air motors.  Redundant banks (if activated simultaneously) increase

the probability of engine rotation during a pinion abutment condition

because it is unlikely that abutment will occur simultaneously on both

banks.  Tandem diesel generators have an even smaller chance of start

failure from pinion abutment because the quantity of air starting banks

is doubled by having the second engine.  Recycle circuitry will retract

the pinions and activate another start attempt if abutment occurs.  This

virtually eliminates a start failure due to pinion abutment; although

starting time will obviously increase.  New York Power and TVA have

reported that they have not experienced any change in starting

reliability since installing the "new" style air start motors.  Note that

the EDG's at both of these sites have redundant banks of air start motors

with pinion recycle circuitry.

                                             REPORT NO. 10CFR21-0076

                                             PAGE: 3 OF 5

                    "NEW" STYLE AIR START MOTOR SALES

Customer            Part Number    Cust.  P.O.            Qty   Ship date

Commonwealth             40047506  47C520                   2    2/27/97

 Ed                      40047506  40D446                   2    3/31/97

                         40047506  43D261                   2    6/02/97

E G & G Rocky Flats      40047506  RS 358781GS2             2    7/25/94

Entergy-River Bend       40047506  95-4-80628               8    12/05/95

Knolls Atomic            40047506  PK0004104 KQ             1    10/24/94

Korea Electric Power     40047506  OH952K204300             1    4/03/96

NYPA-Fitzpatrick         40047506  S 94 66292               2    2/28/95

TVA-Wafts Bar            40047506  P92NJB45165B001/1052012  4    3/01/95

                         40047607  P92NJ845165B001/1142601  1    3/10/97


A replacement air start motor was recommended which did not function the

same as the original part.  Differences between the "old" and "new"

motors were not completely defined by the manufacturer and therefore were

not passed along to the user.  Some of these differences affect the

operation of the engine starting system such that a start motor pinion

gear to engine ring gear abutment results in a start failure.  The

differences are:

Component           "Old" style         "New" style    Reason

pinion piston seal  metal ring.         o-ring.         improved sealing.

pinion piston       a. seal @ 0.380"    a. seal @          a. unknown.

                    from press face,    0.125" from

                                        press face.

                    b. 0.1" groove.     b. 0.242" groove.  b. piston seal


drive housing       a. 4.4375" long.    a. 4.00" long.     a. standardize


                    b. 1/4" npt ports   b. 1/4" npt ports  b. to

                    thru to piston.     neck to 1/8" dia.   accommodate

                                                            o-ring seal

                                                            on piston.


Replace the "new" style air start motors with the "old" style motors.  At

this time, the "old" style starter is only available through a rebuild

program offered by ESL Eventually, I-R may be able to reinstate the "old"

style starter and make it available as a new part and/or modify the

current "new" style starter to make it perform identically to the "old"


1.   Users without redundant starter banks and/or pinion recycle


     Replace the "new" style air start motors with the "old" style motors

     as soon as possible.  It is our understanding that Commonwealth

     Edison has already completed this.

                                             REPORT NO. 10CFR21-0075

                                             PAGE: 4 OF 5

2.   Users with redundant starter banks and/or pinion recycle circuits

     Replace the "new" style air start motors with the "old" style motors

     at earliest convenience, Starting reliability may still be impacted

     by the "new" style motor, particularly if both starting banks are

     not simultaneously activated during starting.  Pinion recycle

     circuitry will most likely prevent a start failure caused by

     abutment, but starting time will be increased.

3.   Users with Grove Flexflo main air valves

     Wisconsin Electric, Point Beach has advised that they have had at

     least two occurrences of pinion shaft shearing on their G01 and G02

     EDG's.  They have also advised that their G01 and G02 EDG's have had

     a history of air start problems which have been attributed to pinion

     abutments.  ESI believes the WE air motor problems have been caused

     by the "roll in" design in combination with the Grove Flexflo valve.

     As discussed previously, this is not a 2-stage valve and therefore

     full starting torque is applied immediately upon activation of the

     valve.  During abutment, the pinion gear and shaft are exposed to

     addition stresses as this torque is applied during the "roll in"

     process.  ESI has not received reports about these types of events

     occurring at other installations; therefore, we are not considering

     this a generic issue.  our recommendation to users with Flexflo

     valves is to review past history.  If problems similar to those

     experienced at Point Beach have occurred, replacement of the Flexflo

     valve with the Graham-White (Salem) valve is advised.

Contact Engine System's Parts department for replacement "old" style


                                                  REPORT NO. 10CFR21-0076

                                                  PAGE. 5 OF 5

                                EXHIBIT 1


                                (2 PAGES)


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