No Fault Found

Mar 02, 2017 • FeaturesManagementCranfield UniversityMaximize EuropeNo Fault FoundJohn Erkoyuncu

The challenge of No Fault Found (NFF) diagnosis is possibly the most frustrating situation for both your field service engineers and customers alike. However, left unchecked NFF has the potential to have an even greater negative impact on a field service organisation. To find out more we spoke to Dr John Erkoyuncu from Cranfield University having earlier seen him give a fascinating presentation on the topic at last year’s Maximize Europe event...

No Fault Found (NFF) can be perhaps the most frustrating end result in any field service visit.

No Fault Found (NFF) can be perhaps the most frustrating end result in any field service visit. The customer’s issue remains resolved, your engineer’s become frustrated at their inability to do their job and perhaps more importantly the someone has to absorb the cost of the truck-roll and the engineers time on site, despite the fact the situation is exactly the same - i.e. no one is any the wiser as to what the problem is in the first place.


At last year’s Maximize event hosted by ServiceMax in Amsterdam towards the end of the year, Dr John Erkoyuncu of Cranfield University gave a fantastic speech on this topic which had the majority of the audience nodding-along in both empathy as they heard him discuss the issue and in agreement as he looked at the potential size of impact NFF can have on our industry.

Field Service News were able to catch up with Erkoyuncu during the conference to find out more about his thoughts on the topic.

What is No Fault Found?

For those unfamiliar to the terminology NFF or sometimes referred to as No Trouble Found (NTF) is the phenomenon whereby an engineer is unable to diagnose why a fault that has been reported is occurring.

As Erkoyuncu explains “No Fault Found is the case where you have a fault that is reported, you go and try to do some diagnosis and you just can’t find a root cause for what the fault is.”

“As a result of this you end up in a situation where it is unclear what you should do next. You could go back and do some more diagnostic testing and try to drill down to what the cause is - but at this point you don’t know if you should be replacing the item of repairing it.”

Often this decision will be locked between the pressures of being time critical and keeping your customers happy on one side, against possibly unnecessary costs - which when stacked up could serously eat into overall profits, on the other.

In fact, NFF is one of the biggest challenges field service companies face in terms of being able to find suitable resolutions whilst being assured these decisions are made based on a standpoint of best practice and well-educated assumptions.

This issue can of course lead to understandable tensions between manufacturer, service providers and their shared customers.

You are in a situation where you as the manufacturer or service provider can’t in fact explain to the customer what is driving their issue. This is in some ways embarrassing and of course the customer doesn’t want to be paying for a service that has not resolved his problem

“You are in a situation where you as the manufacturer or service provider can’t in fact explain to the customer what is driving their issue. This is in some ways embarrassing and of course the customer doesn’t want to be paying for a service that has not resolved his problem.” Erkoyuncu explains.


“So you have problems in terms of who is paying for the service and whose responsibility it is to fix it. It really is a grey area as it is uncertain as to what’s happened or not and whether that falls within the scope of a warranty.”

“It becomes a matter of trust. From the maintainers, to the solution provider to the customer everyone is facing a challenge.”

The changing ownership of NFF This of course can lead to issues in relationships, with faith being eroded amongst the various parties. This in itself has numerous costs but is it possible to identify a tangible cost of NFF?

“We did a survey with the UK No Fault Found working group and what we were trying to understand was what is the cost of no fault found and who bears this cost,” Erkoyuncu explains.

“What we found was that a large chunk of the overall cost, something like 50 to 60% is taken on by the customer. Whilst this is an average figure it just shows that typically the customer has to take on the ownership of No Fault Found.”

“The amount that the OEM and the supply chain takes on varies between 10 and 30% depending on contracts, which is then shared between the supply chain and the OEM.”

“It just shows that typically it is the customer taking on the costs and as we begin to look at outcome based contracts this simply cannot continue. More and more the OEM and the supply chain will have to start taking on the cost of No Fault Found and this is why awareness of this issue is surely going to grow.”

The actual cost of No Fault Found

Whilst there are of course some easily identifiable calculable costs that Erkoyuncu and his colleagues were able to utilise in their study, there are also numerous softer, intangible effects that service providers and OEMs must be aware of also - which can have significant negative impact on a business.

“The intangible aspects are things like reputation” explains Erkoyuncu “Companies could well lose contracts as a result of not dealing with NFF in an acceptable manner, you may lose the trust that you have built over so many years - how can you quantify that? I’m not sure and I’m not sure if anyone could even begin to quantify that.”

When you are estimating things like cost or even R.O.I for being proactive with no fault found we need to find some numbers against the intangible impact as well.

“But when you are estimating things like cost or even R.O.I for being proactive with no fault found we need to find some numbers against the intangible impact as well.”


“For example some people in the audience at today’s session [at Maximize Europe] commented that they felt the customer was really important so they just went ahead and replaced the item.”

“That is the kind of thing you are going to experience just because of that intangible factor.

You don’t know what the fault is, but you do know you don’t want to damage the relationship with the customer.”

How to avoid No Fault Found

It is evident then that NFF could have a significant growing impact for many companies, particularly as outcome based contracts become more in vogue. But is there anything that companies can be doing to help them overcome a problem that is by it’s very essence shrouded in mystery and enigma?

“I think there are multiple things related to this,”Erkoyuncu opens.

Are we designing systems that are fault tolerant to begin with? Is there redundancy built in?

“One is about the design in particular. Are we designing systems that are fault tolerant to begin with? Is there redundancy built in? We’ve got those kind of challenges. For example, you may have a system that has NFF regularly but if that system can self-diagnose and self improve this then that NFF wouldn’t necessarily be a problem.”


“So one area to address is can we design systems that don’t create problems related to NFF?”

“Another area is around behaviour and people,” Erkoyuncu continues.

“Are they being trained properly? Have they got the right incentive structure? For example let’s look at a case where by a field service engineer is paid on the basis of how many times he fixes an item. If they can’t fix it and they can’t define what the problem is - they don’t get paid. So are they then likely to report on NFF properly.”

“There is a big data issue as well and there is also a major issue around whether the data that is available is comprehensive and robust enough - so, there is an additional challenge here too.”

“Therefore, understanding the trends and identifying what the root problems are is quite hard, as the information is not stored properly.”

“Reporting is absolutely a major challenge, as is diagnostic testing. Is it being undertaken properly?

Is the right tool kit being used. Those things are very important as well as you want to be able to very quickly diagnose the conditions,” he adds.

Key steps to overcoming the challenges of No Fault Found

This is obviously a highly prevalent challenge across the industry and one that as mentioned previously is only set to become magnified as business models of OEMs shift towards servitization.

However, here are some key steps that Erkoyuncu recommends that can help field service providers minimise the potential impact of NFF on their own businesses.

“I think the solution to this is a mixture of technology as well as behavioural and process oriented aspects as well,” Erkoyuncu begins.

“I don’t think there is a single solution. We need to look at things like diagnostic testing for intermittent faults. Companies like Rolls Royce and BAE have started using things like environmental chambers. What this does is allow you to simulate the various environmental conditions to allow you to see quickly what the problem is for specific components”

Companies need to consider how their actual technicians providing the maintenance are behaving and then alongside this assess whether their that organisational culture is actually fostering the types of behaviour that they are looking to avoid

“So on one hand, I do think that this is one area [diagnostic testing] that can improve, but I do also think companies need to consider how their actual technicians providing the maintenance are behaving and then alongside this assess whether their that organisational culture is actually fostering the types of behaviour that they are looking to avoid.”


One other very practical piece of advice is to clearly identify your organisations position on NFF within SLA and Warranty contracts.

“This is absolutely and important step,” says Erkoyuncu.

“When you consider the example of FlyBe - they presented some results about the number of NFF they experienced over a set period and they highlighted that about 20% of their service calls were related to NFF.”

“Just looking at this one example you could wipe out all your profits if you ignore the NFF challenge so it should be clearly defined within contracts.”



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