| AD Number | 61-01-03 | Status | Active |
| Effective Date | December 30, 1960 | Issue Date | Not specified |
| Docket Number | Unknown | Amendment | N/A |
| Product Type | ["Aircraft"] | Product Subtype | ["Rotorcraft"] |
| CFR Part | --- - Part 39 | CFR Section | N/A |
| Citation | This information is not available. | ||
| Manufacturer(s) | Sikorsky Aircraft Corporation |
| Model(s) | S-58A S-58B S-58BT S-58C S-58D S-58DT S-58E S-58ET S-58F S-58FT S-58G S-58H S-58HT S-58J S-58JT |
61-01-03 SIKORSKY: Amdt. 238 Part 507 Federal Register December 30, 1960. Applies to All S-58 Helicopters.
Compliance required as indicated.
As a result of a recent failure of a salvaged S1635-20011-2 input bevel gear which caused an autorotative landing, the following must be accomplished:
(a) All input bevel gears (S1635-20011-2) salvaged in accordance with instructions in Sikorsky Service Information Circular No. 1635-1127 Revisions A and E must be retired upon the accumulation of 1,200 hours' time in service since salvage unless reworked in accordance with paragraph (b).
(b) Gears salvaged as outlined in (a) of this directive may be resalvaged, prior to accumulating 1,200 hours' time in service since that salvage, in accordance with (A) of Sikorsky Service Bulletin No. 58B35-3B or the following:
(1) Strip the chrome plate from the gear by reverse electrolysis. (Use Unichrome 80X, manufactured by United Chrome Co., Waterbury, Conn., or equivalent solution.)(2) Measure the bearing journal diameter. If the diameter is more than 0.010 inch below the low limit of the manufacturing tolerance, reject the part.
(3) Perform a magnetic inspection on the bearing area of the gear for cracks, concentrating attention on fillet area; e.g., Magnaflux in accordance with SPEC MIL-I-6868.
(4) If cracks exist, reject the gear.
(5) If no cracks exist, proceed as follows:
(i) Machine and blend the fillet radius at the bearing journal using a radius of blending of 0.150 inch with the maximum depth of undercut equal to 0.010/0.015 inch.
(ii) Again perform a magnetic inspection.
(iii) Shotpeen the area to be chrome plated, in accordance with SPEC MIL-S-13165, at an intensity of 12A2 to 18A2, using S170 shot.
(iv) Bake the gear for five hours at 275 degrees plus or minus 10 degrees F.
(v) Anodically clean the gear so as not to embrittle any carburized areas and to prepare the gear for chrome plating.
(vi) In accordance with FED. SPEC QQ-C-320, Class 2, chrome plate the bearing area to the thickness corresponding to the diameter below lower limits of manufacturing tolerance shown in the following table:
Diameter Below Lower Limits of Mfg. Tolerance
Chrome Plate Thickness
0.006
0.005
0.007
0.006
0.008
0.006
0.009
0.007
0.010
0.007
(vii) Bake the gear for five hours at 275 degrees plus or minus 10 degrees F.
(viii) Final machine the newly chrome plated O.D. to 5.0382/5.0372 inches. After final machining, the chrome plated area shall have a minimum plate thickness of 0.002 inch.
(ix) Perform magnetic inspection after final machining.
(c) Gears reworked in accordance with the provisions of paragraph (b) shall be retired upon the accumulation of 2,400 hours total time in service.
(d) All input bevel gears (P/N S1635-20011-2) that have been salvaged for the first time in accordance with (B) of Sikorsky Service Bulletin No. 58B35-3B shall be retired upon accumulation of 2,400 hours' time in service since salvage.
(Sikorsky Service Bulletin No. 58B35-3B covers this subject.)
This directive effective December 30, 1960.
Revised May 22, 1965.