Trackhobbs Sync for Quickbooks
Trackhobbs has an app for syncing invoices to Quickbooks Desktop using the billing Integration API. There is a little bit of setup required to use it, but once everything is configured (API key, classes, invoice items, etc...) invoices are able to be imported quickly and easily so that you can make use of all of quickbook's reporting features.
One of the key features that made Quickbooks Desktop the natural choice was class based accounting. Trackhobbs does class based accounting by default and records all of your invoices by class so you can track income by aircraft. This means that a profit and loss by class report is automatically a profit and loss by aircraft report.
If you would like to use the Sync for Quickbooks app contact firstname.lastname@example.org to get started.