You might be able to subscribe to the Lexington Law service if there are errors. I had a couple things that didn't belong on my credit report and they got rid of them quickly. In my experience utility companies and banks will not remove shit, but cable companies and medical bills go away. I merged a meter from a mother-in-law cottage into the house's utilities and the $35 final bill went into the void and showed up on my credit report. I had a 30 day late on a $35 credit card bill that I paid online, but the process, for whatever reason, was not recorded. Those two items alone dropped my credit score by 150 points. I discovered a medical bill from a walk-in copay that my insurance didn't reimburse and the bill never made it to me.
The lawyers will advise you to maintain the debt and try to negotiate a "pay off for deletion" with the institution. I found that only worked with a small medical bill. For anything else, pay it off and then hope that it's not worth the collection company's time to respond to the weekly letters requesting further documentation since there's no economic advantage for them to try to collect.
Another note on aircraft financing, if there is any blemish on the title, even from 50 years ago, you may not get financing. The AOPA search only goes back around 10 years and may come back clean. Some loan agencies use aerospacereports which goes back all the way.
I find the credit system very frustrating because I am responsible with my bills, but I travel quite a bit and I've moved occasionally. It only takes a couple bills to get delayed in forwarding or lost to screw up your credit, even if it's a tiny amount compared to your credit flow. It would be nice if there was a central way of notifying you before things go onto your report as it doesn't make sense how they can find you to taint your credit and yet they can't reach you beforehand.