"D" Fare, charged a change fee?
 

Needs some clarification, cant seem to find the answer.

Had a booked round trip flight, EWR-HNL, "b" fare on the outgoing, "d" fare on the return.

Made a change to the return flight (d) fare, and was forced to pay a $150 change fee, because it was on the same ticket as the b fare.

Is this correct?

Generally speaking tickets take on the most restrictive of the fare components on the entire itinerary. So, assuming there is a change fee on the B fare you purchased it sounds correct.

You really would have to read the rules for the fare you purchased to find out what change fees apply. However, IME, UA's D fares were relatively change-fee free up until a few years ago when the fee contagion spread into them, along with most B fares.

The D fare itself is no fee for a change. If I had booked the reservation as a one way, i could have changed for free. But because I booked as part of the round trip with a b fare, I was told the entire reservation defaults to the regulations of the b fare.

That's correct, since you booked it as a round trip. However, there can be drawbacks of booking a trip as two one-ways (even in cases where the price is the same), so neither way is necessarily better than the other. Depends on the situation.

LOL at "fee contagion" :D

I thought that 'defaulting to the most restrictive" was only for cancellations. In other words, if you have different fares on the outbound and the inbound and one carries a cancellation penalty, you can't cancel without a fee. But I also always heard (from my TA, and from this forum) that change fees only apply to the segment you are changing. So if I change the outbound (which carries a fee) I pay the fee. If I change the inbound (which doesn't carry a fee) then I am not charged a fee. You all are saying that this is incorrect. This is pretty confusing. Maybe this varies by airline (I mostly fly LH).