>>>Of course the real problem with a non-instructor completing a 28 day check is what happens if the pilot being checked is not up to standard. The PPL is not qualifiued to decide that and also they are not qualified to provide instruction to bring the pilot up to the required standard. Taking that into consideration, it is hard to see where such a check completed by a PPL would ever stand up in court..........hence one would have to say that unless one uses an instructor it is pointless having such a check.<<<<
I wouldn't use the term 'check' as it could be loaded.
But in my group, a member could be current under the 90-day rule, but be out of group currency (42-days). So under the rules, they fly with me, an non-instructor well-experienced on type.
Although not a test, if they do not display the necessary skill under our group rules I am entitled to stop them from further solo flight. Not pointless at all.
My aircraft, my rules........