Interface ownership and decision rights

Every discipline can finish on time while the integrated system still fails. At a treatment facility, a mechanical engineer sizes a pump for a specified flow, the controls team selects operating logic, and an electrical engineer sizes its supply. If the pump performance curve changes after motor selection, drawings from all three teams may remain individually approved while no longer agreeing. Diagnose an interface conflict by asking what shared data the designs must agree on, who issues the controlled version, and who can accept a deviation. An engineering interface is a technical data agreement: flow, pressure, power, run signal, protection limits, and document revision. Owning a component does not automatically confer authority over a decision spanning disciplines.

Map interfaces before assigning responsibility. For each, record both parties, inputs, accepted output, verification criterion, date, and one decision owner. Two teams may jointly develop options, but do not leave approval of the baseline as 'shared' with no named role. Distinguish who supplies design data, who checks compatibility, who authorizes a baseline change, and who implements it. A responsibility matrix cannot replace an interface record: the former says who can act, while the latter records the value and revision acted upon. If authority to accept a deviation was never delegated to the engineering manager, the adviser cannot create that delegation by writing it in a report. Recommend referral to the authorized decision body and show the schedule implication.

Test ownership against a real change. Suppose a pump supplier raises required power from 75 to 90 kilowatts after a distribution panel was fixed around an 80-kilowatt design input. The question is not merely whether the panel can carry a nominal figure; starting duty, protection, cables, and coordination require review by qualified engineers against applicable standards. The management adviser identifies the missing joint review and formal change request. Record when the supplier notified the project, which revision contains the new requirement, its possible schedule and cost effect, and who can authorize a hold or fund redesign. An adviser without electrical competence must not issue a safety verdict. The adviser can recommend holding affected drawings until the specialist supplies a documented check.

Do not treat a responsibility matrix as a decorative chart. Test it with two questions. When revision mismatch is discovered tonight, who can prevent tomorrow's test? If correcting it adds cost, who can authorize spending? These may be different people. Separating a preventive hold from budget approval can preserve both speed and accountability. Set an escalation threshold: if the parties cannot agree on a revision before the test window, send the decision to the program owner with the delay effect and an option to resequence tests that do not depend on this interface. Do not label delay as waste before comparing it with the risk of testing against wrong data. In the advisory report, distinguish what the recorded test proves from what still needs field verification, and state who updates and signs the interface register.