Severity or Occurrence? Performing an FMEA on Motorcycle Operation

[db]

Performing an FMEA on motorcycle operation. One of the failure modes would be falling off the bike. A failure mode of that would be striking the head on the road. The effect would be severe, to say the least. So, we perform some error proofing by adding a helmet. Now when you hit the road there is less chance of head injury.

The attached photo should show actual results of me falling off my Harley (with help of a white tail deer). I can tell you with all certainty there were no injuries to my head. The question is.... Did the severity change because there was no injury, or would you say that the helmet kept my head from actually impacting with the road, so the occurrence is what dropped?

I say the severity changed. But would like your opinion.

BTW, my leathers kept me mostly road rash free, but when the bike and I cart wheeled over the deer, the bike landed on my right leg. Now I am an automatic candidate for enhanced, detailed screening at airport security.

 

[John Broomfield]

Re: Severity or Occurrence?

db,

As a result of your FMEA you took preventive action by wearing the helmet.

As the failure mode was falling off bike your wearing of the helmet made no difference to the frequency of occurence but it made a lot of difference to the severity of loss.

John

 

[Bev D]

This is one of "round peg square hole" issues with the restricted FMEA format.

Hitting your head is an effect. And the use of a helmet is NOT a mistake 'proof' device as wearing a helmet is voluntary in some states and even in those where it is a legal requirement, some people will choose to not wear their helmet. Additionally, very hard impacts may leave your head intact but your body in pieces and smears. an intact head on a dead body is still a dead head.

If we are being rigid in our FMEA, the severity doesn't change and neither did the occurence rate of the BIKE failure to hold the rider/passenger on board. technically, the use of a helmet is considered a mitigation to reduce the severity of the effect in some users. This aspect is not captured by the standard FMEA form except as a note in the controls/mitigation section.

 

[AndyN]

I'd also suggest that 'falling off' isn't the correct failure mode - you didn't fall off, the deer collided with you...and increasing occurrence in MI, where the deer almost out number rats!

 

[db]

Although I do like your answer, the following, although quite true, is not a very comforting thought... We need an "ouch" smiley thingy.

Additionally, very hard impacts may leave your head intact but your body in pieces and smears. an intact head on a dead body is still a dead head.

 

[Bigfoot]

i'd also suggest that 'falling off' isn't the correct failure mode - you didn't fall off, the deer collided with you...and increasing occurrence in mi, where the deer almost out number rats!

andy - you must live somewhere close to lansing cause the deer way out number the rats along the southern border of mi.

 

[Bev D]

Of course you mean the buckeye rats! Not the Hoosier rats...

 

[Jimmy123]

The effect and severity is what it is. In my opinion it‘s safety relevant S=10 with and w/o a helmet, because people died also with helmet. The occurrence of the cause is what it is. Occurrence can be only reduced by a fence or gun or drive slowly.

 

[GRP]

If the failure mode is "falling off bike", wearing a helmet is not a preventive action. A suitable preventive action would be reducing the speed, avoiding areas with deer, attaching a sidecar to the motorcycle.

Depending on who you ask, preventive actions act on the cause or on the combination of "failure mode and/or cause"

 

[John Broomfield]

Of course.

The failure mode we have in mind when we don our crash helmet is:

“Head hits highway pavement”.

That may have been predicated by:

“Driver failed to watch out for a bike (even with its headlight on)”