Competency-based interview questions ask a candidate to describe something they have actually done, rather than what they would do in theory. For a manufacturing hiring manager that is the quickest way to find out whether a maintenance engineer really can fault-find under pressure, or whether a quality engineer really has closed out a customer complaint. This article explains the format, how to score it, and gives fifteen questions grouped by role, each with what a good answer includes.
What a competency-based interview is
A competency is a behaviour that predicts good performance in the job: problem solving, attention to detail, communication, teamwork, leadership and so on. A competency-based interview tests each one by asking for a real, specific example from the candidate’s past work. The interviewer then probes that example until the candidate’s own contribution, the actions they took and the result are all clear.
The format works because past behaviour is a better guide to future behaviour than opinions are. It also makes interviews fairer: every candidate is asked the same questions and judged against the same standard, so the decision rests on evidence rather than on who the panel warmed to.
Most candidates will have prepared for this style. Some may have read our guide to the format, how to prepare for a competency-based interview, which walks through the structure and the kind of examples interviewers expect. Expect prepared answers, and use follow-up questions to get beneath them.
How to score the answers
Decide the competencies before the interview, usually four to six, and write one or two questions for each. Agree what a strong, acceptable and weak answer looks like for every question before anyone sits down with a candidate. That short description is your scoring anchor.
During the interview, listen for four things in each answer: the situation, the task the candidate owned, the actions they personally took, and the result. Candidates often talk about what the team did. Ask “what did you do?” until you can separate their contribution from everyone else’s.
Score each answer straight after the question on a simple scale, for example 1 to 4, against the anchors you wrote. Score independently, then compare notes as a panel. Keep the sheets: they are your evidence if a decision is ever questioned, and they show you which questions are actually telling candidates apart.
Competency questions test behaviour. They do not test whether someone can read a hydraulic circuit or write a control plan. Pair them with a practical exercise or a technical walk-through; our post on how to assess technical skills in engineering roles covers how to build that side of the interview.
Fifteen competency-based interview questions by role
Pick the questions that match the competencies you have agreed. Three or four well-probed questions tell you more than ten skimmed ones.
Maintenance engineers and technicians
- Tell me about a breakdown where the fault was not obvious. How did you find it?
What a good answer includes: a logical sequence (symptoms, checks, what was ruled out and why), use of drawings or diagnostic tools rather than guesswork, and an honest account of how long it took. A strong candidate explains what they would check first next time.
- Describe a time you had to make a line safe before you could work on it, and production was pushing you to hurry.
What a good answer includes: isolation and lock-off carried out in full, a clear conversation with the shift manager about why, and no sign that the candidate would ever skip a step to save minutes. Pressure should feature in the story without changing the outcome.
- Give me an example of a repeat failure you stopped for good.
What a good answer includes: evidence they looked for the root cause rather than fitting another part, a change to the planned maintenance schedule, a spares holding or a procedure, and a measurable drop in call-outs afterwards.
- Tell me about a time you handed over a partly finished repair at the end of a shift.
What a good answer includes: a written handover, a conversation with the incoming engineer, the machine left in a known safe state, and a follow-up the next day to check it was finished. This tests communication and ownership as much as technical skill.
Quality engineers and inspectors
- Describe a customer complaint you investigated. What did you find and what changed?
What a good answer includes: containment first (what was quarantined and where), then a structured investigation, a corrective action that addressed the cause, and verification that it worked. Listen for the candidate closing the loop with the customer.
- Tell me about a time you had to stop a shipment or reject a batch, and someone senior disagreed.
What a good answer includes: the candidate held their ground on the evidence, escalated through the proper route, and stayed professional. A good answer also shows they looked for a way to recover the situation, such as a sort or a concession agreed with the customer, rather than simply saying no.
- Give me an example of an audit finding you owned. How did you close it?
What a good answer includes: a clear understanding of what the finding actually meant, a corrective action with an owner and a date, and proof that the fix stuck at the next audit. Vague answers about “updating the procedure” are a warning sign.
- Describe a time you used data to persuade production to change something.
What a good answer includes: the measure they used, how they presented it to people who do not live in spreadsheets, and the change that followed. The best answers show the candidate understood production’s constraints and worked with them.
Production supervisors and team leaders
- Tell me about a shift that went badly wrong. What did you do in the moment, and what did you do afterwards?
What a good answer includes: a calm order of priorities (people, then safety, then the plan), clear communication up and down, and a proper review afterwards that changed something. You are listening for composure and for learning, not for a story with a tidy ending.
- Give me an example of an operator whose performance you had to turn around.
What a good answer includes: the candidate found out why before acting, set clear expectations, gave the person a fair chance with support, and followed the company’s process if it did not improve. Avoiding the conversation, or going straight to discipline, are both weak answers.
- Describe a time you had to hit a delivery with fewer people than the plan needed.
What a good answer includes: realistic reprioritising, early warning to the planner or the customer, flexible use of trained people, and honesty about what was not achieved. A candidate who claims to have delivered everything with half a team is usually leaving something out.
- Tell me about an improvement you led on the shop floor, start to finish.
What a good answer includes: a problem the team cared about, operators involved in the solution, a simple before-and-after measure, and the change still in place months later. Improvements that quietly reverted after the project board came down do not count.
Engineering managers
- Describe a project you delivered late or over budget. What happened and what did you change?
What a good answer includes: ownership without blaming suppliers or the board, an early and honest conversation with stakeholders, a specific lesson applied on the next project. A candidate who has never had a project slip either has not run many or is not telling you.
- Tell me about a time you had to win support for capital spend.
What a good answer includes: a business case built on numbers the finance team could check, options rather than a single ask, and an understanding of what the decision makers cared about. The result matters less than the quality of the case and how they handled a no.
- Give me an example of how you developed an engineer in your team.
What a good answer includes: a named development need, a plan that mixed stretch work with support, time the manager personally gave, and where that engineer is now. This separates managers who build teams from those who only manage workload.
Common mistakes with competency-based interview questions
- Accepting a hypothetical. “I would isolate the machine first” is an opinion. Ask for the time they did it.
- Letting “we” stand in for “I”. Team stories hide individual contribution. Keep asking what the candidate personally did.
- Scoring at the end. By the fourth candidate, the first one’s answers have blurred. Score each answer as you go.
- Different questions for different candidates. That removes the comparison the format depends on, and it is hard to defend if a decision is challenged.
- Treating a polished answer as a strong one. Rehearsed answers tend to be tidy. Probe the detail: who else was involved, what went wrong, what they would do differently.
- Ignoring the technical side. Competencies tell you how someone works; they do not confirm they can do the job. Add a practical element.
- Leaving the candidate cold. A good interview is still a conversation. Explain the format at the start, give people time to think, and leave room for their questions.
For more on structuring the whole interview, from preparation to feedback, read our guide to interviewing techniques for engineers.
Getting the shortlist right first
Good interviews only pay off when the people in the room are worth interviewing. As a manufacturing recruitment agency we screen candidates against the competencies you set before they reach you, so your interview time goes on people who can show the evidence. If you would like help building a competency framework for a role, or a shortlist to put it to work on, book a call with us.
