United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9708140366

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ESI                                               ELECTRO MOTIVE

                                              AUTHORIZED DISTRIBUTION




PHONE: (919) 977-2720

FAX: (919) 446-1134


DATE:          07/14/97

COMPANY:       Office of Nuclear Reactor Regulation

FAX NUMBER:    301/415-1887

ATTENTION:     Vern Hodge

REFERENCE:     Report #10CFR21-0076-IR

FROM:          Michael Nuding - Quality Manager


Dear Sir:

A copy of our report 10CFR21-0076-IR is attached which addresses a

potential defect with EMD air start motors.  This is an interim report

which will be finalized after we complete our investigation into this


Should you have any questions, please let us know.

Yours very truly,


Michael Nuding

Quality Manager

                                   Report No.  10CFR21-0076-IR

                                                JULY, 14, 1997

                      10CFR21 REPORTING OF DEFECTS

                           AND NON-COMPLIANCE

                             INTERIM REPORT

COMPONENT:     EMD Air Start Motors #40047506 & #40047507

SYSTEM:        Standby diesel generators with EMD diesel engines

CONCLUSION:    To be determined

PREPARED BY:                                      DATE:

               Donald D. Galeazzi

               Engineering Manager

REVIEWED BY:                                      DATE:

               Michael Nuding

               Quality Assurance Manager

                                        REPORT NO. 10CFR21-0076-IR

                                        PAGE: 1 OF 4


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.  This is an interim

report; a final report will be issued after EMD completes its

investigation into this matter.  We expect to have this issue completed

by mid August, 1997.

Design changes were initiated by I-R to the air motors which resulted in

part number changes by EMD.  The "new" style (#40047506 & #40047507) air

motors were issued by EMD as replacements for the "old" style air motors

(#8367694 & #8377435 respectively).  #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 rotation.

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 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).  After performing our own testing on an old style air

motor and discussing air motor operation with Ingersoll-Rand, it appears

this has not actually been occurring

The old style starter (EMD 8367694) received pinion engagement air and

"ported" (sent air signal out to engage the pinion of the adjoining air

motor or to activate the main air valve) after the pinion moved less than

1/8".  Under most starting scenarios, the pinion gear will properly mesh

with the engine ring gear as an activate signal is issued to the main air

valve; 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.  On the rare occasion abutment occurs, the gears

"fall into" mesh as the air motor begins to rotate.  The following

sequence occurs:

     1.   Gears abut.  Distance from end of pinion gear to engine ring

          gear is 3/16".  For abutment to occur, pinion gear therefore

          moved 3/16".  Engagement air "ports" after pinion gear movement

          less than 1/8"; therefore, an activate signal is sent to the

          main air valve.

     2.   Main air valve receives activate signal from air starter pinion

          line.  The main air 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.

                                        REPORT NO. 10CFR21-0076-IR

                                        PAGE: 2 OF 4

The new style starter (EMD 40047506) received pinion engagement air and

"ported" after the pinion moved at least 1/4".  With an initial 3/16" gap

between the end of the pinion gear and the edge of the engine ring gear,

an activate signal would not be sent to the main air valve during pinion

abutment and therefore the engine would fail to start.


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


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



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.  This is unusual

for an EMD nuclear safety related diesel generator.  Units with redundant

banks of starting motors and recycle circuitry are not affected by this

notification because these features virtually eliminate a start failure

caused by pinion abutment.  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.  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.

                    "NEW" STYLE AIR START MOTOR SALES

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

Commonwealth Ed.     40047506      47C520              2    2/27/97

                     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      OH962K204300        1    4/03/96

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

TVA-Watts Bar        40047506      P92NJB45165B001/

                                   1052012             4    3/01/95

                     40047507      P92NJB45165B001/

                                   1142601             1    3/10/97

                                        REPORT NO. 10CFR21-0076-IR

                                        PAGE: 3 OF 4


Changes to the air starting motor were made by the manufacturer which

were not completely defined and therefore were not passed along to the

user.  Some of these changes may 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.  This condition is only applicable

to units which do not utilize redundant air start motor banks and which

do not have pinion recycle circuitry.  The design changes 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


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

                                           groove         change

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


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

                       thru to piston      ports neck     o-ring seal on

                                           to 1/8" dia.   piston


Corrective action has not yet been determined.  The "new" style air

motors appear to meet the original design intent of the EMD starting

system; although, it is not clear why the "old" style air motors "ported"

air with less than 3/16" pinion travel.  Two (2) possible corrective

actions are:

1.   Preferred action

     Add a redundant bank of air start motors to the left bank of the

     engine.  In addition, modify the control circuitry to incorporate

     pinion abutment recycle circuitry.  These features are standard on

     all EMD safety related diesel generators fabricated by Engine

     Systems and were standard for most units fabricated by EMD for

     nuclear applications.

2.   Alternate action

     To make the new style air motors perform the same as the old style

     motors, the distance from the end of the pinion gear to the engine

     ring gear must be increased.  Adding a shim between the air motor

     mounting face and the engine starter mounting bracket will

     accomplish this.  The shim thickness should be approximately 1/8"

     thick and can be fabricated from carbon steel.  This thickness will

     enable the pinion air to "port" on gear abutment and still provide

     adequate pinion gear engagement with the engine ring gear.  Note:

     This action is not preferred because adding the shim defeats the

     original EMD design intent to achieve pinion engagement of both air

     motors before applying main starting air to the motors.

                                             REPORT NO. 10CFR21-0076-IR

                                             PAGE: 4 OF 4

                                EXHIBIT 1


                                (2 PAGES)




                           AIR STARTING SYSTEM


A single air starting motor, Fig. 4-1, is used on 8 cylinder engines, while

12, 16, and 20-cylinder engines use dual air starting motors, Fig. 4-2.  An

installation can also be equipped with single or dual electric motors.

Figure 4-1 "Single Motor Air Starting System" omitted.

Figure 4-2 "Dual Motor Air Starting System" omitted.

The basic engine starting system utilizes air motors with pinion drive to

flywheel ring gear.  Operational control is the same for either single or

dual air starting motor starting system.  An ENGINE START pushbutton is

located on the engine control cabinet.  The pushbutton is a single contact

switch which remains closed during the engine cranking period.

The starting system control of turbocharged engines is interlocked to

require the turbocharger lube oil (soak back) circulating pump to be

running, and the governor SPEED CONTROL to be set for idle speed before the

engine may be started.

Refer to Fig. 4-3 and the following paragraphs for operation of a basic

dual air starting motor starting system.


Upon receiving a start signal, the solenoid valve is energized to allow air

from the tanks to pass through the solenoid valve to the pinion gear end of

the lower starting motor.  The entry of air moves the pinion gear forward

to engage with the engine ring gear.  Movement of the pinion gear uncovers

a port allowing air pressure to be released to the upper starting motor

which, in turn, engages its pinion gear with the engine ring gear.  Both

pinion gears being engaged, the air released from the uncovered port in the

upper motor.  The released air opens the air relay valve, which in turn

opens the air starting valve, and releases the main starting air supply.

Starting air passes through the air line lubricator, releasing an oil-air

mist into the starting motors, automatically lubricating the motors.  The

multivane motors drive the pinion gears, rotating the ring gear, cranking

the engine.

The system is designed so that unless both pinion gears are engaged no

attempt can be made to start the engine with one motor.  There is also a

shutoff valve in the system which is manually operated.  When maintenance

is being performed, the shutoff valve is closed to prevent inadvertent

cranking of the engine.

Section 4

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


The air starting system 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 be

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 lubricator.

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 fillers should not be used

in the lubricator.

Refer to applicable Engine Maintenance Manual for maintenance data on

starting motors and unattached accessories.


Page Last Reviewed/Updated Thursday, March 29, 2012