If the engineers arn't the 'specially trained personnel' - who are?
In my book, the ONLY people specially trained are our Airport Fire Service, who are required on occasion to inspect undercarriage following an incident. They are wearing FULL Personal Protective Equipment (PPE) including a full-face vizor and helmet, completely enveloping fire-proof suit, boots, gloves etc. Even then, they insist on confirmation via RTF that the relevant engine is shut down and the park brake applied before approaching.
They also approach on a fore-and-aft line, so that if the wheel rims/sidewalls of the tyres let go, they don't collect the bits. If you've ever seen a wheel rim go, you'll know what I mean!
Anyone wearing less PPE certainly isn't 'specially trained'
TheOddOne