AD 72-07-07

72-07-07 DOWTY ROTOL: Amdt. 39-1417. Applies to all propellers with blade root sizes Nos. 20 and 30. These propellers are installed on but not limited to Fairchild F-27 Series; Fairchild Hiller F-227 Series; Armstrong Whitworth Argosy Type AW 650 Series; Vickers Viscount 745 and 810 Series; and Grumman G-159 Series airplanes.

Compliance is required as indicated unless already accomplished.

To prevent possible fatigue failure of propeller blades or blade bearings as a result of loss of bearing pre-load due to discrepancies in the ground tracks or improper assembly of the propeller blade bearing, accomplish the following:

(a) For propellers with any bearing identified by one of the Bearing Identification Numbers listed in subparagraph (3) that has not been last reground by an FAA-approved repair facility subsequent to April 21, 1971, or by the bearing manufacturer, comply with paragraph (c)(1) within the next 400 hours' time in service after the effective date of thisAD, or at the next disassembly of a bearing from a blade for cause, whichever occurs sooner. Thereafter, comply with paragraph (c)(2) at the following intervals:

(1) For propellers for which there is a scheduled blade overhaul, at each disassembly of a bearing from a blade for cause, including disassembly at overhaul.

(2) For propellers for which there is no scheduled blade overhaul, at each disassembly of a bearing from a blade for cause, and at intervals not to exceed 5,000 hours' time in service on a blade from the last inspection.

(3) Bearing Identification Numbers:

BRGS. BRGS. BRGS. BRGS. BRGS. BRGS. 11309 10449/R 16726 16331/R/R 18305/R 4696/R/R 16350 9660/R 15071/R 947/R/R 18328/R

13098 13917/R/R 15337 13345/R 17078/R N16672/R 18077/R

N15311 1237/R/R/R 2280/R/R

2847/R/R

N8225/R N17430 3670/R/R N13981 N15427 16970/R 11781/R N17368 7801/R/R N14011

16498/R

N17313 2629/R N13980 N4629/R 15523/R/R 12825/R N17424

N13977 20448/R 15959/R N17829/R

N16327

12794/R

N11240/R N15257/R N16078/R N16167/R 5901/R/R 10571 N21240N/R 14731/R N14495/R N16490/R

7060/R/R N9730/R N16898/R 17082/R 5756/R 18119 1298/R

N16532 16831/R N18287 3626/R/R

21243

15309/R N18236 18081/R 11766/R 16790 3258/R 16512/R N12714 11838/R/R

9180/R 4416/R

20441/R/R N18094 2489/R 15302/R N10966 N11149 14352/R

3054/R 16339/R

N3682/R/R

18055

N15574 N11761 1400/R/R 11751/R/R 16295 N13837 16179/R/R N14938

11346/R/R N13821

14163 7049/R N11778/R/R N13822 4786/R/R/R 14165/R 14734

N13833 1989/R/R 12749/R/R 1851/R/R/R/R N16977/R N20911N

315/R/R 13347/R 9048/R

4709/R N9296

4354/R/R N4689/R

14019/R/R N15489/R 20045N/R

N15890 13969 N434/R/R 21280N/R/R 13993/R N20340 N16773 14386/R/R 15567 17018 11764/R 10422/R/R N16706 15220/R14364/R 10554/R N16647/R

5801/R 2753/R/R 14213/R

N15285 11765 N11358/R/R

13559/R/R 16981/R 15275 12038 N21248N/R 12746/R

20449/R/R 15538 11754/R N18103 12571/R/R N15703 N21048N/R 9668

13853/R N15691 20823/R/R

4131/R/R

11756 N16858

5235 5155/R N7479/R

N17408

N5007/R/R

N11724/R

(b) For all other propellers, comply with the following:

(1) For propellers for which there is a scheduled blade overhaul -

(i) Comply with paragraph (c)(1) at the next disassembly of a bearing from a blade for cause, including disassembly at overhaul; and

(ii) Thereafter comply with paragraph (c)(2) at each disassembly of a bearing from a blade for cause, including disassembly at overhaul.

(2) For propellers for which there is no scheduled blade overhaul -

(i) Comply with paragraph (c)(1) at the next disassembly of a bearing from a blade for cause or before the accumulation of 5,000 hours'time in service on the propeller from the last inspection, whichever occurs sooner; and

(ii) Thereafter comply with paragraph (c)(2) at each disassembly of a bearing from a blade for cause and at intervals not to exceed 5,000 hours' time in service on a blade from the last inspection.

(c) Inspect blade bearings in accordance with either subparagraph (1) or (2), as applicable.

(1) For the initial inspections required by paragraphs (a) and (b) disassemble the propeller to the stage where the assembly of blades complete with bearings are removed from the hub and inspect each blade bearing in accordance with paragraph (d).

(2) For the repetitive inspections required by paragraphs (a) and (b), inspect affected blade bearings in accordance with paragraph (d).

(d) Measure and record the bearing torque and the center race spigot mean diameter before and after removal of bearing pre-load; and compute the spigot expansion, in accordance with the procedures specified in Dowty Rotol Service Letter No. SER/SSL/1, dated August 12, 1971, or an FAA-approved equivalent. If the spigot expansion, for a bearing size and blade bearing assembly specified in Columns 1 and 2, respectively, of the following table, is -

(1) Equal to or greater than Expansion Value A (Column 4), the bearing assembly, blade, and blade bolt may be returned to service.

(2) Less than Expansion Value B (Column 5), remove the bearing assembly, blade, and blade bolt from service and mark them in a manner that will prevent their further use.

(3) Less than Expansion Value A, but equal to or greater than Expansion Value B (Column 5), before further operation of the blade, blade bolt, and bearing assembly return the bearing assembly to Dowty Rotol, Inc., Arlington, Virginia, or Dowty-Rotol Ltd., Service Department Cheltenham Road, Gloucester, England, for a load-expansion torque test to determine the remaining service life of the blade and blade bolt. The measurements of bearing torque and the mean spigot diameter before and after removal of the blade bearing preload required by this paragraph must accompany the parts.

(Col. 1) Bearing Size (Col. 2) Blade Bearing Assembly (Col. 3) Normal Spigot Expansion (Col. 4) Expansion Value A (Col.5) Expansion Value B

RA38965 .0055

RA38965Z to .0050 .0035

RA38965Z-1 .0060

No. 20

RA54100 .0050

RA54100Z to .0040 .0030

RA54100Z-1 .0055

RA57099 .0040

RA57099Z to .0035 .0025

RA57099Z-1 .0045

No. 30

RA22355/1 .0035

RA22355/2 to .0030 .0022

.0040

(e) An inspection performed following any period in service since the last installation of the propeller, may be accepted in lieu of the initial inspection required by paragraph (a) to be performed within the next 400 hours' time in service after the effective date of this AD, if the records of thatinspection are submitted to an FAA Maintenance Inspector and he determines that the inspection included a computation of spigot expansion performed in accordance with the procedures specified in paragraph (d) which established that the spigot expansion values were equal to or greater than the applicable Expansion Value A (Column 4) specified in paragraph (d) for the bearing size and blade bearing assembly.

This amendment becomes effective March 29, 1972.