78-24-03 SOCIETE NATIONALE INDUSTRIELLE AEROSPATIALE: Amendment 39- 3347. Applies to Model SA 330 Puma helicopters, certificated in all categories, that have accumulated less than 500 hours total time in service on their main gear boxes and have not incorporated Puma Modification AMS 07.51.103.
Compliance required before further flight, unless already accomplished, but helicopter may be flown in accordance with FAR 21.197 and 21.199 to a base where the required work can be performed.
To prevent failure of the main gear box input reduction gears due to excessive vibration, replace the main gear box with a gear box incorporating Puma Modification AMS 07.51.103 or accomplish the following:
(a) Determine the acceleration spectral level of the input reduction gears in accordance with the accomplishment instructions of Puma SA 330 Service Bulletin No. 01.21, dated July 12, 1977, or an FAA-approved equivalent.
(b) If the acceleration spectral level found during the test required by paragraph (a) of this AD measures 52db or more, replace the forward input reduction gears with gears incorporating Puma Modification AMS 07.51.103, or an FAA-approved equivalent.
(c) If the acceleration spectral level found during the test required by paragraph (a) of this AD measures less than 52db, the input reduction gears may remain in service if the operator receives written information from Aerospatiale that a spectral analysis shows the gears to be acceptable.
(d) Continue to comply with paragraphs (a) through (c) of this AD at intervals not to exceed 20 hours time in service until the gears have been replaced with gears incorporating Puma Modification AMS 07.51.103, or an FAA-approved equivalent.
This amendment is effective November 24, 1978, as to all persons except those persons to whom it was made immediately effective by the telegram dated May 19, 1978, which contained this amendment.