There may be lots of reasons for needing to hire a project management consultant. For example, there will be times when a project requires the help of specific project management expertise not available within the organisation. This may stem from when the project manager has not performed well or it might simply be because of the nature or the complexity of the project which requires additional expertise. Another common reason is when a project manager leaves a project and interim management is needed while recruiting a new project manager. In all these circumstances it might be useful to hire a project management consultant to help get the project back on track and provide help and guidance to the project manager.
There will be a range of skills and abilities that you will want from a project consultant and it is particularly important when recruiting that you find someone who can compliment the skills of the existing project manager. A role or task profile would be useful with a person specification drawn out from it. When advertising you can concentrate on the complimentary skills required. You will need to shortlist against your prepared criteria and then begin a selection and recruitment process. Interviews will be a necessary part of the process but they are notoriously poor predictors of performance. You will need to consider some objective information to assist in the decision making process.
One objective source of skill level is the qualifications held by the applicant. Good project consultants will be qualified and the current industry standard is PRINCE2. This methodology deals solely with the process for project management; project managers will need to learn techniques through other means, either on the job or through formal training. Some post PRINCE2 training will be required also. The other well recognised qualification for project managers is the APM. This compliments the PRINCE2 qualification as it deals less with process and concentrates on techniques.
By far the best indicator of the skill of a project management consultant is the experience of having rescued or advised on other projects successfully. They should be able to provide demonstrable evidence of having advised on similar issues in the past and be able to clearly explain how they helped manage the project back to meeting its objectives. It is best to tease the detail of this information out of the candidate at interview. It is still useful to call for references, but more and more references are becoming bland and uninformative.