Musel 14, an ex-Air Force Boeing Vertol CH-21 (No. 52-8683) formerly of the 1001st Helicopter Squadron at Boiling and Andrews Air Force Bases in the Washington, D.C. area. The squadron was the last flying unit at Boiling before the base was closed to all flying in late 1968. The CH-21 was the primary aircraft used in USAF support missions. From Vertiflite, September/October 1975 (page 10).