Honeywell auxiliary power units are a series of gas turbine auxiliary power units (APU) made by Honeywell Aerospace. Honeywell started manufacturing APUs in the early 1950s and since then they can be found on many aircraft.[1] Over the years Honeywell have produced more than 95,000 APUs and more than 36,000 are still in service.[2]
The 131-9D initially was designed for the McDonnell Douglas MD-90 series; the 131-9B became standard equipment on Boeing 737NG; the 131-9A on the Airbus A320 family.[4] The 131-9C has entered service aboard the Airbus A220 (formerly Bombardier C-Series). The 131 Series uses a two-stage axial turbine and a single generator which starts the APU.[5]
331 Series
The 331 series are found on many wide-body Boeing and Airbus aircraft and the Honeywell 331-200 introduced several new technologies such as digital electronic control and the eductor for oil cooling, which eliminated the need for cooling fans. The development of a turboprop derivative from the Honeywell TPE331 also reduced development time and production costs.[6][7]
Its applications include Airbus A220 -100 and -300 series, A300, A330, A340, Boeing 767 and 777, Bombardier CRJ700/900/100, Comac C919 and Irkut MC-21.