I am a Navy veteran and one of the things that really bugged me about the Navy's preventative maintenance program was how utterly pointless I perceived most of it to be. Everything has a procedure - written by who knows - but seemingly by someone who lacked common sense. It all just seemed like busy work to me and I chocked it up to "the navy just has too many people with too much time on their hands so they invented PMs to give people a purpose." On the one occasion I brought this up to my superior I was told that I wasn't paid to think and that somebody alot smarter than me had written these and I was to follow them to the "T" or risk punishment.

one example - vacuuming out sealed enclosures. These enclosures are milspec, designed to be submerged in salt water indefinitely without leaking (sealed with an indestructible gasket and sealed screw fasteners every 2 inches) , yet you have to go in monthly and vacuum it. I was on the boat for 3 years doing this monthly PM which works out to 36 times and I never encountered a speck of dust. It was my opinion that I was causing more harm than good - constantly working the screws back forth causing them to wear out faster.

Now I work maintenance in a manufacturing facility and it's the same story. I can't count how many times I've been pulled off what I consider to be a more important task to go do some mundane PM full of wordage like "Check motor", "Check motor brushes", "check belt, replace if worn", "check brake pressure".

IMO, it would be less stressful, more cost effective, and more efficient to just fix things as they break or wear out - that is, Unless you have a machine producing an expensive product that would become damaged, or a production line that would become seriously askew by one component failing. On a simple machine that is not part of another process, I see no reason whatsoever to waste time checking motor brushes quarterly when the stupid things last like 15 years. If the motor brushes were bad, you would know it, because you would have been called out there for the motor acting up. If the belt was bad, you would know it, because you would have been called out for a shaft not spinning.

Consider in a plant with 100+ machines that all have monthlies & quarterlies, how much down time you cause for preventative maintenance & how much down time you could avoid by triaging unneeded preventative maintenance. I think you should just order spares of wear parts and replace them as they fail.

another point - replacing wear items before they have failed - consider over the life of the machine how much money you waste by replacing brushes/belts/bearings/seals/hoses/gears/clutches/brakes/sometimes motor, etc. before they have absolutely failed. You are not getting the most out of your parts.

I have heard that in some plants they take it a step further and quarterly/ yearly they megger all their motors and keep the insulation resistance values recorded over time. There is a downward trend in the resistance and once they reach a certain point, they replace the motor - ludicrous in my book.

So, what's your opinion? Am I way off base? please let me know so I can feel like it's not all pointless toil.

 

I'm not military, never have been.

I worked machine maintenance for 10 years. I never thought it was pointless. Much like changing the oil in your car, maybe it won't help long term, but the odds are against your engine not taking damage are slim without.

With military stuff a failure in the field can mean death, lot of it, all on the wrong side. It doesn't hurt to look at the equipment now and again either, even on mission critical hardware.

 

The life of a machine, is determined of the maintenance you put into it.

My father, a retired Navy officer, is driving around in an 1982 Mercedes 190, which soon will get to 350 000 km.

He is changing parts before they break or gets worn out. That way, the car is in perfect condition.

I say maintenance is a good thing, and that we could be better at it.

 

I think you may be overlooking something in your verdict against preventive maintenance.

In the interest of maintaining battle readiness, the maintenance you are so quick to dismiss may mean the difference between victory or defeat.

Just as you rely on the battle readiness of your fellow crew members, your life and that of your fellow crew members hinges on the reliable operation of the equipment on board your ship.

hgmjr

 

I guess it depends on what is more expensive: The accumulated down time of the machine and the cost of its spares or a possible (even rare) failure and the unscheduled unavailability of it.

Two examples:

Home inkjet printers are so cheap nowadays that even one service session costs almost as much as the printer itself. As a result replacing parts is more expensive than the device itself. It's operation isn't critical and as a result it is more profitable to wait for it to fail and buy a new one.

On the other hand, the operation of a defibrillator is crucial to an operating room. Even if the manufacturer said its minimum life expectancy is 2 years, would you wait for it to fail in order to replace or service it?

P.S. In nerdegutta's father's case, a weighted factor, the love for his car, makes regular service a favourable choice, instead of buying a new, modern car.

 

I think my post made me sound like I condemn all maintenance. That's not so. There are some things, like changing oil in gearboxes & such, which is time proven to prolong the life of the machine and I don't have a problem with that. The importance of maintaining life & mission critical equipment doesn't escape me either; I was on a submarine, where the malfunction of 1 valve or hatch seal could spell the end of all of us onboard - & those were the things that I wouldn't have a problem doing a monthly PM on, or even daily.

Thanks for the input.

 

One must weigh the costs of PM against the consequences of in-service failure. My guess is that the expected consequences of a combat failure far outweigh E1 pay. Outside the military, you gotta determine how much reliability is worth to you. I used to work on Charlie Daniel's tour bus pretty regular like. His driver, Dean Tubbs, was highly demanding and all us techs questioned his sanity. But, you know what? That bus was built the first year they started putting DD series 60's in them, which was 1994. The bus drove like a dream, probably has a million miles on it now (literally), and he almost never experienced problems on the road. Was it worth it? Judging by the problems experienced by other old coach owners, I would say yes. But you would have to ask the man footing the bill. My question is, why, as a maintenance man, do we care, as long as we get paid?

 

another point - replacing wear items before they have failed - consider over the life of the machine how much money you waste by replacing brushes/belts/bearings/seals/hoses/gears/clutches/brakes/sometimes motor, etc. before they have absolutely failed. You are not getting the most out of your parts.

It is a tad awkward to be involved in doing failed parts replacement while under attack. Or changing out a failed maggie in the SPS 10 when in a tight passage in fog.

It's not all about you. Some jobs are not as critical as others, but the survival of your ship/aircraft, and every other unit that is involved in an operation depends on your stuff working perfectly every time it's needed.

Our only failure during a 7 month deployment off the coast of Vietnam was a failure that somehow ate every PN junction in one chassis of a computer. Even so, we operated with a reduced capability the one night before the replacement came out from the states.

When someone's life depends on your stuff working, no amount of time spent on maintenance is too much. Gundecking PMS is the same as murder if the equipment fails and gets someone killed.

 

PM is important, and I think there is little serious debate about that. Sure, there are situations, like the military, where much of the PM may be "keep busy" work. But in the private sector, it is unlikely a company is trying to waste money.

The hard part in setting up PM is in getting the intervals right. One needs to balance the time needed to prevent an indeterminate number of failures with the cost of an unplanned downtime. Quite often, there are no data to show that monthly PM will be more cost effective over a long period compared to, say, a semi-annual PM plus unscheduled maintenance. Thus, the periods are set arbitrarily and unfortunately sometimes become incorporated in OSHA or other regulations. Changing such regulations is extremely difficult. (I was involved in such work for over 30 years.)

If the PM frequency is not covered by regulation, I would suggest doing it, keep records of the need to actually replace or repair, and then discuss potential changes with your supervisor. If the PM is done monthly, you will probably need data from at least 2 years to get it changed. Other users of the same equipment may be able to add to your data. That's how were got data on over 400,000 lots of supplies over 10 years showing no failures, so we could get the testing intervals mandated by a Federal regulation changed.

In any event, complaining about or trying to short-cut the PM will not help your performance appraisal. Doing something constructive with data to support your suggestion might get you a promotion.

John

 

One must weigh the costs of PM against the consequences of in-service failure. My guess is that the expected consequences of a combat failure far outweigh E1 pay. Outside the military, you gotta determine how much reliability is worth to you. I used to work on Charlie Daniel's tour bus pretty regular like. His driver, Dean Tubbs, was highly demanding and all us techs questioned his sanity. But, you know what? That bus was built the first year they started putting DD series 60's in them, which was 1994. The bus drove like a dream, probably has a million miles on it now (literally), and he almost never experienced problems on the road. Was it worth it? Judging by the problems experienced by other old coach owners, I would say yes. But you would have to ask the man footing the bill.

Good points there, I guess if the money man wants then he gets it.

My question is, why, as a maintenance man, do we care, as long as we get paid?

An obvious question, but not one I have an obvious answer for. Maybe I care too much. I fancy myself being an improver of things, not a just maintainer & follower of step-by-step instructions. That is pretty much the exact opposite of my job description. I am just now realizing that maybe I'm in the wrong line of work.

It is a tad awkward to be involved in doing failed parts replacement while under attack. Or changing out a failed maggie in the SPS 10 when in a tight passage in fog.

I never experienced a similar situation, which maybe why I see things the way I do.

When someone's life depends on your stuff working, no amount of time spent on maintenance is too much. Gundecking PMS is the same as murder if the equipment fails and gets someone killed.

I never said I gundecked PMS, only that I thought the majority of it was pointless.

PM is important, and I think there is little serious debate about that. Sure, there are situations, like the military, where much of the PM may be "keep busy" work. But in the private sector, it is unlikely a company is trying to waste money.

You would think so, but from my point of view it looks like that's exactly what they're doing.

The hard part in setting up PM is in getting the intervals right. One needs to balance the time needed to prevent an indeterminate number of failures with the cost of an unplanned downtime. Quite often, there are no data to show that monthly PM will be more cost effective over a long period compared to, say, a semi-annual PM plus unscheduled maintenance. Thus, the periods are set arbitrarily...

I think that's exactly what I'm dealing with. I learned the other day that a majority of the P.M. sheets were generated by prior mechanics/technicians following a big push to "get onboard with a regular maintenance schedule". I'm thinking maybe they just puked out whatever they thought sounded good onto a paper and called it monthly, and it's been that way for the past 15 years. Those guys don't work here anymore so I can't ask them. In any case I don't think anybody did a study & crunched the numbers for each PM as to whether or not it's beneficial.

...but then again I thought the same thing about the Navy's PMs.

...and unfortunately sometimes become incorporated in OSHA or other regulations. Changing such regulations is extremely difficult. (I was involved in such work for over 30 years.)
If the PM frequency is not covered by regulation, I would suggest doing it, keep records of the need to actually replace or repair, and then discuss potential changes with your supervisor. If the PM is done monthly, you will probably need data from at least 2 years to get it changed. Other users of the same equipment may be able to add to your data. That's how were got data on over 400,000 lots of supplies over 10 years showing no failures, so we could get the testing intervals mandated by a Federal regulation changed.

Ok, sounds good.

In any event, complaining about or trying to short-cut the PM will not help your performance appraisal. Doing something constructive with data to support your suggestion might get you a promotion.

John

Thanks for the advise John.



Well you guys are all pretty smart and like most other people I've discussed this with, you seem to mostly disagree with me. I think that says something for my argument. That being said, I don't think it will be any easier for me to convince myself that I'm not wasting my time while doing PMs. (and don't worry, I plan to actually do my pms, as I always do)
Thanks again!

 

Nearly every PC I've had die was due to heat sink fins on the video, CPU or RAM being coated to clogged with dust, raising the temp, causing the fan to fail. A chain reaction.

As far as equipment inside hermetically sealed enclosures, I can see an issue with opening it often maybe damaging the seal, but the rest of the list seems "normal" to prevent catastrophic failures. Usually when checking belt tension, brushes, etc, a good tech will often see something that is 'not quite right' before it completely fails.

 

I'n my world, Preventative Maintenance includes the process of determining intervals. In a large part, it's investigative and not necessarily the work itself. When I engage in PM activities, I will typically generate work orders that are subsequently followed up by other techs. My job more or less, is evaluation. This evaluation includes not ony the current state of equipment, but it's predictive life cycle within process demands. The value of such activity creates a base where equipment and processes are evaluated for capitalized aquisitions. Breakdown maintenance can never do that.

 

... the rest of the list seems "normal" to prevent catastrophic failures. Usually when checking belt tension, brushes, etc, a good tech will often see something that is 'not quite right' before it completely fails.

I see your point and I know that half the purpose of the PM is just to get the tech inside the machine, in a position to notice things that are "not quite right" before they fail completely. What I was originally referring to was non-life threatening and non-expensive product threatening manufacturing equipment. I was saying that I don't see the point in looking for things that are "not quite right" and "catching things before they fail." an example:
A 1000gal shop air compressor - I see the point in changing the compressor oil according to the manufacturer's recommendations, periodically testing the pressure relief valve, and bleeding off moisture daily; I don't see the point in going every month, taking the belt guard off & checking the belts for cracks & compression, meggering the motor, and checking current draw. When the belts fail, just replace them; when the motor fails, just replace it; no need for proactive/preventative maintenance there (but keep spares around, you should do that anyways).

 

Letting a piece of machinery operate until failure is much more likely to cause damage to other parts of the mechanism, leading to a more expensive and work intensive replacement session.

Would replacing a belt before it broke be better than running it till is snapped and damaged the belt dive cover and maybe lodge in the pulley in such a way as to create friction with the motor shaft(now running wildly over speed due to no load) and possibly overheating the bearings or bending the pulley?

Letting equipment go to failure is NOT something to encourage.

 

Letting a piece of machinery operate until failure is much more likely to cause damage to other parts of the mechanism, leading to a more expensive and work intensive replacement session.

Would replacing a belt before it broke be better than running it till is snapped and damaged the belt dive cover and maybe lodge in the pulley in such a way as to create friction with the motor shaft(now running wildly over speed due to no load) and possibly overheating the bearings or bending the pulley?

Letting equipment go to failure is NOT something to encourage.

Well said, example shot down. I'm just not thinking far enough into this.

 

I put 32 years in with a major aircraft manufacturer, working as a maintenance person and in various levels of supervision. During my tenure, PM's were a very important function in dealing with our machines. After retirement from the company, the facility was sold to a British firm. From all accounts of the folks remaining at the facility, PMs have become a thing of the past and hard failures are the norm. Large DC brush type servo motors seem to be bearing the brunt of failures due to lack of PM. Sadly, many of these motors are no longer available. Simple cleaning and brush replacement would have extended their life considerably.

 

I learned the other day that a majority of the P.M. sheets were generated by prior mechanics/technicians following a big push to "get onboard with a regular maintenance schedule".

All preventative maintenance schedules have their roots in the Manufacturer's recommendations.

Take a motor-generator. Cumin's recommened by hours or annually. Without a power failure, the most the generators ran were four hours per month or forty eight hours per year per generator. I had two motor generators and eight HVACs, and one Automatic Transfer Switch to change from commercial power to station generators. That was to ensure the Loran-C signal kept emitting. After I retired, they put in an UPS (Unterruptible Power Source) to keep the 800 kW peak transmitter on air for the 8 or so seconds it took for the generator to start, get up to speed, and take the load.

Yes, PMS programs are important. They also need "start" with the manufacturers recommendations, and modified from there within the framework of the local enviroment and the time between failures.

Do your research. I don't think any PM program is designed for busy work. Bear in mind, if you find the staff doing less PMs, you could find your staff with less people. This is a double edge sword.

Prior to joing the military, while a junior and senior in High School, I worked in the engineering dept at a small radio station doing PMs. Yes, failures cost the station money. If the station wasn't on air, the commercials weren't being played, and the money wasn't flowing in to pay the workers. Your business model has critical elements. Those certainly get the preventative maintenance.

Another point of PM, athough subtle, is you have your eyes and hands in the area alot. This bodes well when there is a failure, your not locating test points as you've already been there done that. If you waited for corrective maintanence, you might not know instinctivly where those test points are ... adding to the time to repair the failed equipment/subsystem.

 

I put 32 years in with a major aircraft manufacturer, working as a maintenance person and in various levels of supervision. During my tenure, PM's were a very important function in dealing with our machines. After retirement from the company, the facility was sold to a British firm. From all accounts of the folks remaining at the facility, PMs have become a thing of the past and hard failures are the norm. Large DC brush type servo motors seem to be bearing the brunt of failures due to lack of PM. Sadly, many of these motors are no longer available. Simple cleaning and brush replacement would have extended their life considerably.

I am reminded of the joke where the ex-engineer wanted $1,000,000 dollars for fixing a machine was required to detail the invoice.

ChalK: $1
Knowing where to put Chalk Mark: $999,999

 

Nowadays, for all practical purposes, it does not pay to do preventive maintenance. If something fails...fix it, or replace it, mostly replace it with something, better & cheaper. Look at computers, printers & TV's, you simply replace...not repair. In many cases, you cannot repair as parts are un-available or are so high priced, it just doesn't make any sense. Now with fuel prices heading toward $ 5.00/ gal., it makes no sense to waste your time and money trying (in vain) to find parts to fix something. I violated this principle last year in repairing our Jenn-Aire electronic range, by diagnosing the problem and buying the appropriate parts over the Internet; delivered to my door by UPS. So it depends upon the problem you are facing.

Cheers, DPW, Everyone's knowledge is in-complete...Albert Einstein

 

Tell that to a poor grunt trying to defend his ship or vehicle under attack with a piece of equipment going balky, or a manager on a factory floor loosing about $1M a day (or more) because some critical machine died. Not a good argument IMO. How about your heating or air conditioner? Wait until the unit dies to change filters? Or may oil changes, car's don't really need em. PM is an absolute requirement in almost every setting.