Amphibious helicopter The HUP-2 was able to taxi forward or backward on water, regardless of wind direction. The CH-46 Sea Knight and its Canadian variant, the CH-113 Labrador, can land on water and rest for up to two hours in calm water. The rear sponsons hold two of the three landing gear units as well as self-sealing fuel tanks. The helicopter began service with the United States Marine Corps in 1962, and with the Canadian military in 1963, and is used to carry cargo and combat troops. The Boeing CH-47 Chinook was made sufficiently watertight to allow it to land on water
Boeing Chinook (UK variants) was to be based on the CH-47B but the order was cancelled in a review of defence spending in November 1967. UK Chinook procurement ambitions were revived in 1978 with an announced requirement for a new heavy-lift helicopter to replace the Westland Wessex. Thirty Chinooks were ordered at a price of US$200 million. These helicopters, comparable to the CH-47C with Lycoming T55-L-11E engines, were again designated Chinook HC Mk1, and entered service in December 1980. Eight more Mk1s were delivered from 1984 to 1986 with the CH-47D's Lycoming T55-L-712 turboshafts. The replacement of the Mk1's metal rotor blades with aluminium