Rev Rul. 2003-116, 2003 I.R.B.1083 (11/17/2003) PDF
This ruling concludes that a helicopter is not an airplane for purposes of section 147(e) of the Code which provides that a private activity bond is not a qualified bond if issued as part of an issue and any portion of the proceeds of such issue is to be used to provide any airplane, etc.

Rev. Rul. 2008-47, 2008 I.R.B. 760 (09/29/2008) PDF
Section 6621 of the Internal Revenue Code establishes the rates for interest on tax overpayments and tax underpayments.

Rev. Rul. 2008-50, 2008 I.R.B. 1098 (11/10/2008) PDF
This revenue ruling provides various prescribed rates for federal income tax purposes for November 2008 (the current month).Table 1contains the short-term, mid-term, and long-term applicable federal rates (AFR) for the current month for purposes of section 1274(d) of the Internal Revenue Code.