Maintenance Release with an Open Defect
An aircraft is due for release after a scheduled inspection. The inspection found a small fuel leak at a hose fitting, classified by the maintenance manual as a 'minor seep' that may be deferred for up to 10 flight hours under a minimum equipment list (MEL) entry. The aircraft has a 6-hour charter planned tomorrow. The leak rate is within the manual's deferral limit, but the fitting is in a zone that is difficult to access, and the engineer suspects the seep has been present for several days. The operator pressures the engineer to sign the release because the charter is already sold. The engineer must decide whether to release under the MEL, rectify now, or ground the aircraft, and must document the basis for the decision.
1. Evaluate whether the MEL deferral is legitimately available in this situation.
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The MEL deferral is available only if the conditions in the manual are met. The leak is classified as a minor seep within the deferral limit, and the planned flight is 6 hours against a 10-hour deferral, so on the face of it the numerical conditions pass.
But the MEL entry is not a blanket permission. The engineer's suspicion that the seep has been present for several days matters, because a seep that is progressing may no longer be a stable minor defect. The deferral assumes the condition is not deteriorating. The engineer should verify the leak rate against the manual's limit and check whether the fitting shows progression before treating the MEL as satisfied. If progression is evident, the numerical deferral no longer applies and the entry cannot be used. The decision must rest on condition, not just on the 10-hour number.
2. Recommend a decision and explain how the engineer should document and communicate it.
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The engineer should not release on the MEL if there is any sign of progression. The correct action is to rectify the fitting now if parts and time allow, or to ground the aircraft until it can be rectified, because a 6-hour charter on a suspect, possibly progressing leak is not a defensible risk.
Commercial pressure from the operator is not an airworthiness consideration and must not influence the release. The engineer should document the observed leak rate, the comparison with the manual limit, the suspicion of progression, and the reasoning for refusing the deferral. The operator should be told plainly that the aircraft is unavailable and why, with the rectification plan and expected return to service. If the engineer does defer, the documentation must show the condition was verified as stable and within limits, with the 10-hour clock recorded. Either way, the record must let a regulator reconstruct the judgement.