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Offline Rennhack

Why a Nuclear Plant Engineer Cannot Afford to Change a Lawnmower Spark Plug Himself

1)   Spark plug wrenches come in different styles. Some have foam inserts, some don’t. Some are deepwell and some are short. Some are 6 point and some are 12 point. Some are hardened and some are chrome plated. Some are ¼” drive and some are ½” drive. Which one should be used?
a)   Are there papers or studies currently available on this subject?
b)   Have inquiries been made to the industry (OPEX) or to users groups?
c)   Does the vendor manual direct use of a specific wrench?
d)   Does the wrench manufacturer recommend use on lawnmower sparkplugs?
e)   Is the wrench available in tool storage and if not, has its purchase been budgeted?

2)   Is there an approved procedure for changing the spark plug?
a)   Have all prerequisites, precautions, and limitations been satisfied?
b)   Is it the current revision?
c)   Is it “continuous” use or “reference” use?
d)   Has the worker been trained and certified to perform this job?
e)   Is the test director / maintenance foreman fit for duty?

3)   Break away torque needs to be calculated to determine when the plug should come loose.
a)   Is there acceptance criteria for calculated torque tolerance?
b)   If actual required torque is less than calculated, what is the impact on the engine system? Are there other tests required to mitigate the findings?
c)   Should an IR be written along with an OPEX report?
d)   If actual required torque is greater than calculated, what is the impact on the engine system? Are there other tests required to mitigate the findings?
e)   How is torque wrench calibration verified?
f)   Do we need both a pre and post calibration of the torque wrench?

4)   Is a prejob brief required? Does it need to be documented?
a)   How will communication be established with other people in the area?
b)   Has the clearance order been hung and walked down?
c)   Have the MSDS sheets been reviewed for the chemicals which may come into contact with the worker during the evolution?
d)   Is emergency equipment such as fire extinguishers and eyewash available?
e)   Is a fire watch required?
f)   Will air sampling be required for LEL and O2 levels?
g)   Is a GFCI available for portable lighting and power tools?
h)   Does the extension cord have a current quarterly inspection tag on it?
i)   Is a fragnet required for this job?
j)   Is all personal safety equipment available?

5)   After the spark plug is removed, the as-found condition must be evaluated and recorded to ascertain if a negative trend is developing.
a)   Was the plug changed too early?
b)   Was the plug changed too late?
c)   What is the optimal maintenance frequency?
d)   Has a cost evaluation been done to correlate the material and manpower costs against increased engine performance?
e)   What was the as-found gap? If not per vendor specification, should a root cause be performed to determine why the discrepancy exists?
f)   Is the engine manufacturer’s recommended gap the same as the spark plug manufacturer’s recommended gap?
g)   Were there indications of too lean or too rich a combustion?
h)   Was there indication of oil consumption?
i)   How will the threads in the cylinder head be cleaned?
j)   Are there FME covers staged to cover the head while the sparkplug is removed?
k)   Are QC hold points required during the evolution?
l)   Is the cylinder considered to be a pressure vessel and does it need to be inspected as an IDNS component by the ANI?

6)   What spark plug should be reinstalled?
a)   What is the vendor recommendation?
b)   Heat range?
c)   What is the required gap?
d)   How is gap measured and do we need a pre and post calibration on the measuring instrument?
e)   If the specified brand of spark plug is not available, is a parts evaluation needed to substitute with another brand?
f)   Has the sparkplug been placed on reserve?
g)   Will a megger test be required prior to installation? What is the criteria?
h)   Will an electrical continuity test be required prior to installation?
i)   Document a visual like-for-like comparison between the old plug and replacement plug and resolve any discrepancies.

7)   Should a lubricant be used on the sparkplug threads?
a)   Has the compatibility with both the plug material and engine head material been evaluated?
b)   Does the vendor recommend a lubricant?
c)   Have all precautions on the MSDS been satisfied?
d)   Has there been an evaluation done to determine what, if any, impact the lubricant will have on electrical continuity?
e)   Will the lubricant break down at running temperatures? If yes, has the chemistry of the breakdown by-products been evaluated?

8)   Should a sealing washer be used on the sparkplug?
a)   What does the vendor recommend?

9)   What torque should be used to reinstall the spark plug?
a)   Should a hot retorque be performed? At what time interval?
b)   Does the job require concurrent or independent verification of correct installation?

10)    What post maintenance tests need to be performed?
a)   Leak test? At what throttle setting? Hot or cold?
b)   Thermography?
c)   Engine performance on a dynamometer?
d)   Combustion products analysis to determine if fuel / air ratio and dwell settings are correct?
e)   Functional test of mower? What are the initial test conditions concerning grass height, moisture content of grass, air temperature, humidity, throttle setting, fuel brand and grade, and mower speed.

As you can see, changing a lawnmower spark plug is a very challenging job for a nuclear plant engineer and may not be cost justified. If after evaluation, a contracted professional is determined to be more cost effective, is the contractor on the ABL and has his Q.A. program been evaluated and audited?  Has the requisition fo.r…  purch a se…….b..b..e.a,mfaadf jaspetq]tgq\w3 4=965 om5jg a’d;gfla Fkaogf msdg . AAAAAAAAAAAHHHHHHHHHHHH SCREW IT!! JUST PUT THE DAMN THING IN!


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