grew and two more 737s joined the fleet as replacements. NAC was one of Boeing's earliest 737 customers, the first outside the United States and West Germany. Some minor engineering tweaks to the 737 occurred during the first few years as the type developed. This included the changing of its engine's clamshell reverse thrusters over the exhaust pipes to the more familiar 'bucket' style that stayed with the 737-200 type to the end. This also helped with reducing soot emissions of the earlier model. Boeing changed the hydraulic and flap configuration of the 737 in 1973 and sold to the airline at a bargain price the last 737-200 in the original format, becoming ZK-NAJ. Regional jet trials The Boeing 737 had settled into routine service when NAC launched a small regional jet study to replace the Viscount. This included the Russian Yakolev Yak 40, Fokker F28 'Fellowship' and the still-experimental Hawker Siddeley HS146. Unfortunately, the country fell into an economic slump caused by the 1973 oil crisis and the United Kingdom joining the European Economic Community causing a drop in passenger numbers with NAC selling one of its brand new 737s after only six months in service. NAC quietly dropped the regional jet proposal and more F27-500s were purchased. List of aircraft operated by NAC List of fleet survivors Ex-NAC Dragon Rapides, Fox Moths, and DC-3s still fly in private and charter operator hands. Below is a list of known surviving NAC aircraft. Uniforms In 1965–66, Barbara Penberthy of Auckland was the first New Zealander to design the airline's uniform. Created as a departure from the 'uniform look', it was a high-fashion two-piece suit and blouse with matching coat and hat. The fabric was all-wool barathea, dyed to a colour named 'golden cloud' specially created for NAC; a name by which the uniform came to be known. The suit jacket would be removed before onboard aircraft duties. The blouse consisted of three-quarter sleeves, a self-pleated panel down the front, three decorative pearl buttons at the neck and double cuffs with pearl cuff-links. The new 9ct gold NAC staff hat-badge, designed by NAC staff, framed NAC's godwit symbol within a circle. Discarding sleeve braid, ranks were then denoted by the number of small silver stars on the bar of the jacket insignia also designed by airline staff. Stockings were in a colour specially created for the uniform and named 'cirrus'. The