73-18-02 HAWKER SIDDELEY AVIATION, LTD.: Amendment 39-1706. Applies to Hawker Siddeley Model BH-125 and DH-125 airplanes equipped with overhauled oxygen cylinders.
Compliance is required within the next 14 days after the effective date of this AD, except as provided in paragraph (c), and thereafter at each replacement of an oxygen cylinder with an overhauled oxygen cylinder.
To prevent the possible burst failure of overhauled oxygen cylinders, P/N WKA 29396/GR14, WKA 29396/GR22, WKA 31393, and WKA 31394, due to the overhaul stamp impression being located on a critical area of the cylinder, accomplish the following:
(a) Visually inspect the surface of the oxygen cylinder for evidence of stamp impressions indicating the date of the overhaul or letters designating the overhaul agency.
(b) If stamp impressions are found during an inspection required by paragraph (a), on the cylinder shoulder, either (1) outboard of a radius of 3 inches from the cylinder center, or (2) inboard of a 3 inch radius and accompanied by local distortion in the hemispherical profile at the stamp impression, before further flight, replace the cylinder with a serviceable part of the same part number, or an FAA-approved equivalent.
(c) If the oxygen system is to be recharged before accomplishment of the inspection provisions of this AD, the oxygen system charge must be limited to not more than 50 percent of normal full quantity, and a placard must be installed adjacent to the oxygen system charging point, stating, "System Contents Must Not Exceed 1/2 Full At Any Time."
(d) The placard required by paragraph (c) may be removed when it is determined by an inspection in accordance with paragraph (a) that the oxygen cylinders have no stamp impressions on the cylinder shoulder, outboard of a radius of 3 inches from the cylinder center, and if there is a stamp impression inboard of a 3 inch radius, that there is no local distortion in the hemispherical profile at the stamp impression.
This amendment becomes effective August 28, 1973.