Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Human Factors; Company Policy; Procedure
After engine start; we noticed a mechanical problem that necessitated a return to the blocks. After coordinating with Ramp; we taxied back to the blocks. Immediately upon setting the parking brake; maintenance personnel approached the aircraft with stairs to board before either engine has been shut down. We shut down the engines; and before we could complete our checklists; the mechanics were already in the cockpit asking questions about the mechanical issue. Even at idle thrust these engines are dangerous and there was no need for ground crew to be approaching an aircraft before the flight crew has had an opportunity to shut down the engines. Two of them were wearing hats which could have easily been sucked into the operating engine; but their proximity to the engine could have had a much more devastating result.When we spoke to the crew and asked why they felt so hurried to approach the airplane; they told us that they weren't sure if we were going to shut down the engines and that they remained outside the yellow lines. If an aircraft returns to the blocks; there is no need to have Maintenance approach to board before engines have been shut down. While I understand that a mechanical delay can elicit a hurried response to get the aircraft in the air; there is no need to rush. Hasty reactions are very dangerous. Furthermore; it takes just a few minutes to shut down the engines and [to] allow the flight crew to finish their shutdown checklists. These 2 or 3 minutes are minimal to the often hour or so delay caused by a block turn back. As such; nothing can be gained by adding such unnecessary risk to the aircraft; or worse; to ground personnel. In such cases I believe it is imperative that before approaching any aircraft with the intent to board; and getting near an engine; that ground crew allows the flight crew time to perform their shutdown procedure and any necessary checklist(s).
B767 First Officer reported Maintenance dangerously approaching the aircraft before the engines were shutdown.