Editing ATR 72 (section)

== Design ==
[[File:Pratt & Whitney Canada PW123 retouched.jpg|thumb|left|A [[Pratt & Whitney Canada PW100]] series engine]]
The ATR 72 is a [[turboprop]]-powered [[regional airliner]], capable of accommodating a maximum of 78 passengers. It is powered by a pair of [[Pratt & Whitney Canada PW100]] turboprop engines, which drive an arrangement of four or six-bladed [[Propeller (aeronautics)|propellers]] supplied by [[Hamilton Standard]]. Earlier models of the ATR 72 are equipped with the older PW124B engine, rated at {{convert|2400|shp|kW|lk=on|disp=flip}}, while later-built aircraft are powered by the newer PW127 engine, rated at a maximum of {{cvt|2750|shp|disp=flip}} to achieve improved "[[hot and high]]" takeoff performance. It can land and takeoff in high airports with short runways like [[Andorra–La Seu d'Urgell Airport|Andorra Airport]]. It employs carbonfibres for 30% of the wing by weight, for a 20% weight reduction.<ref>{{cite web |url= https://www.flightglobal.com/FlightPDFArchive/1988/1988%20-%200652.PDF |title= ATR72 first with carbon-fibre wing |work= Flight International |date= 19 March 1988 |access-date= 20 April 2017 |archive-url= https://web.archive.org/web/20170421000337/https://www.flightglobal.com/FlightPDFArchive/1988/1988%20-%200652.PDF |archive-date= 21 April 2017 |url-status= live }}</ref>

In a standard configuration, the aircraft does not have an [[auxiliary power unit]]; when present it is installed within the C4 cargo section. Most operators of the ATR 72 equip their aircraft with a propeller brake that stops the propeller on the No. 2 (right) engine while allowing the turbine to continue running, to provide both airflow and electrical power to the aircraft while on the ground. (This arrangement is referred to as "Hotel Mode".)

In the majority of configurations, passengers board the ATR 72 using the rear door, a relatively unusual configuration for a passenger aircraft, while the front door is typically used for the loading and unloading of cargo; early customer Finnair intentionally ordered its ATR 72s with a front passenger door so that it could utilize the [[jet bridge]]s at [[Helsinki Airport]], while operator [[Air New Zealand]]'s standard rear door aircraft can use jet bridges at airports with this equipment.{{Citation needed|date=July 2017}} While passengers are boarding or disembarking, a tail stand is set into place as standard procedure to guard against the aircraft nose lifting off the ground.