59-05-02 de HAVILLAND: Applies to All Model 104 "Dove" Aircraft With Modification PP.173 Embodied.
Compliance required as soon as possible but not later than March 30, 1959.
(1) A case has been reported where faulty readings were obtained from the dipstick used in an oil tank P/N 4LT.475A/1, in which Modification PP.173 was embodied. This would result in low oil content which, on prolonged flights, might give rise to oil starvation with consequent engine seizure.
(2) Within the period stated above, dipsticks must be removed from oil tanks with Modification PP.173 embodied and reworked as follows: (a) Measure along the dipstick a distance of 4.15 inches from the base and file a notch or deep score mark at this point. (This position also falls 0.65-inch above existing one-half mark.) (b) Obliterate the existing one- quarter and one-half marks. (c) Add a stamped arrow pointing to the notch or score mark followed by this marking "6 US gallons minimum accurate reading".
(3) The above rework must be accomplished on spar oil tanks prior to fitment to aircraft.
The British Air Registration Board considers this mandatory. The FAA concurs with this action and considers compliance therewith mandatory.
(de Havilland TNS CT (104) No. 158 Issue 2 covers the same subject.)