Not really sure if "Is this notifiable" is the right question.
Is it significant? Yes
Are there learnings we could take from the event? Yes
We would need additional background fact for context as the question you pose does not contain sufficient evidence to arrive at the answer you are seeking.
Your answers to questions appear incomplete also.
Was it the fuel pump of the stationary truck while the vehicle was being serviced in the yard or a fuel pump being transported as part of the freight inventory?
How much did it weigh?
Was anyone injured?
Could it have been catastrophic?
Without thorough investigation then you could be looking at a repeat with more significant consequences and be left in the position of not having taken all practicable steps.
Get into it pre(another)incident.

Hi Rob.
Could I meet you for a coffee early next week?
Phil Wilkes

IEC standard 62508 "Human aspects of dependability" and HSE guide "Reducing error and influencing behaviour". Are these them?