Hughes Helicopters Service Information Letters by Hughes Helicopter Manuals Sale $30.00 | / SKU 40610:R Printed Manual - $30.00 Download - $30.00 Printed Manual Download Size 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart Hughes Service Information Letters. Starts with Letter No. 2A-1-1000 Dated May 19, 1964 and ending in Letter No. L-38 Dated Jan 31, 1968. 288 Pages