Part 21 Report - 1997-521
ACCESSION #: 9711210027
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ENGINE SYSTEMS, INC.
301 South Church St., Suite 100 / P.O. Box 1928 / Rocky Mount, NC 27802-
1928 / Telephone: (919) 977-2720 / Fax (919) 446-3830
TELEFAX
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:
Sincerely,
ENGINE SYSTEMS, INC.
Michael Nuding,
Quality Manager
Quality Performance With Pride
Section 4
Fig.4-3 "Typical Air Starting System Diagram" omitted.
MAINTENANCE
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
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 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
10CFR21 REPORTING OF DEFECTS
AND NON-COMPLIANCE
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
SUMMARY:
This report supersedes our interim report 10CFR21-0076-IR dated July 14,
1997.
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
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 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.
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. 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
DEFECT:
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
change.
drive housing a. 4.4375" long. a. 4.00" long. a. standardize
parts.
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.
CORRECTIVE ACTION:
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"
style.
1. Users without redundant starter banks and/or pinion recycle
circuitry
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
starters,
REPORT NO. 10CFR21-0076
PAGE. 5 OF 5
EXHIBIT 1
EMD AIR START SYSTEM DESCRIPTION
(2 PAGES)
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