Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
ACCESSION #: 9708140366
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ESI ELECTRO MOTIVE
AUTHORIZED DISTRIBUTION
ENGINE SYSTEMS, INC.
1220 SOUTH WASHINGTON STREET
ROCKY MOUNT, NC 27801
PHONE: (919) 977-2720
FAX: (919) 446-1134
TELEFAX
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
PAGES INCLUDING COVER SHEET: 8
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
matter.
Should you have any questions, please let us know.
Yours very truly,
ENGINE SYSTEMS, INC.
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
SUMMARY:
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.
COMPONENT:
EMD #40047506 I-R #150BMPD88R543335 For left hand (standard) rotation
engine.
EMD #40047507 I-R #150BMPD88L543336 For right hand (reverse) rotation
engine.
CUSTOMERS AFFECTED:
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
DEFECT
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
face.
b. 0.1" groove b. 0.242" b. piston seal
groove change
drive housing a. 4.4375" long a. 4.00" long a. standardize
parts
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:
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
EMD AIR START SYSTEM DESCRIPTION
(2 PAGES)
SECTION
4
ELECTRO-MOTIVE STATIONARY POWER
AIR STARTING SYSTEM
GENERAL
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.
DESCRIPTION
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.
MAINTENANCE
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.
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