Commonwealth legislation

AD/ENST 28/9 Amdt 4 - Main Rotor Mast

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

4/10 complexity

This Airworthiness Directive requires owners/operators of Enstrom F‑28 helicopters fitted with specified main rotor transmission or shaft part numbers to inspect the upper shaft fillet for cracks, nicks or scratches (dye‑penetrant), polish out nicks/scratches under 0.005 inch, and replace transmissions or shafts if defects meet thresholds. It imposes short compliance times (before further flight; within 5 hours) and recurring intervals (25/100/300 hours) and allows a terminating action by installing specified large‑radius fillet parts (Note 1) (see c–d; Compliance).

JSON API

Deep dive

Want the full deep dive?

Zoe can write the in-depth analysis on top of the summary above: how it works, who it affects and what each part actually does.

Current sections

Direct links to the current provisions in AD/ENST 28/9 Amdt 4 - Main Rotor Mast.

Enstrom F-28 Series Helicopters

AD/ENST 28/9 Amdt 4 (continued)

(c) If the transmission is part number 28-13101-1 or \-1-R, or part number 28- 13101-3 or \-3-R:
(i) Dye-penetrant inspect the shaft upper fillet for a crack, a nick, or a scratch.

(ii) Polish out nicks or scratches less than 0.005- inch deep.

(iii) If the shaft is cracked or has a nick or scratch 0.005- inch or more deep, replace the transmission with a serviceable transmission having a large radius shaft fillet before further flight.
(d) Replace transmission, part number 28-13101-1 or \-1-R, or 28-13101-3 or \-3- R with a serviceable transmission having a large radius shaft fillet.

Note 1: Installing a serviceable transmission with a shaft, part number 28-13104-1 or -1-R, Revision K, L, M, N, P, R, or S, or part number 28-13140-1 or -1-R, is terminating action for the requirements of this Directive.

Note 2: FAA AD 2002-08-03 Amdt 39-12710 refers.

Compliance: 1. Before further flight after 28 August 2002, unless already accomplished.

2. Before further flight after 28 August 2002, unless already accomplished.

3. a. Before further flight after 28 August 2002, unless already accomplished.

b. Unless the initial inspection is already accomplished, before further flight after 28 August 2002. Thereafter at intervals not to exceed 25 hours time in

service.

c. Unless the initial inspection is already accomplished, within 5 hours time in service after 28 August 2002. Thereafter at intervals not to exceed 100 hours time in service.
d. Unless already accomplished, within 300 hours time in service after 28 August 2002 or at the next overhaul, whichever occurs first.

This Amendment becomes effective on 28 August 2002.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

Enstrom F-28 Series Helicopters Enstrom F-28 Series Helicopters

Enstrom F-28 Series Helicopters

AD/ENST 28/9 Amdt 4 (continued)

(c) If the transmission is part number 28-13101-1 or \-1-R, or part number 28- 13101-3 or \-3-R:
(i) Dye-penetrant inspect the shaft upper fillet for a crack, a nick, or a scratch.

(ii) Polish out nicks or scratches less than 0.005- inch deep.

(iii) If the shaft is cracked or has a nick or scratch 0.005- inch or more deep, replace the transmission with a serviceable transmission having a large radius shaft fillet before further flight.
(d) Replace transmission, part number 28-13101-1 or \-1-R, or 28-13101-3 or \-3- R with a serviceable transmission having a large radius shaft fillet.

Note 2: FAA AD 2002-08-03 Amdt 39-12710 refers.

Compliance: 1. Before further flight after 28 August 2002, unless already accomplished.

2. Before further flight after 28 August 2002, unless already accomplished.

3. a. Before further flight after 28 August 2002, unless already accomplished.

b. Unless the initial inspection is already accomplished, before further flight after 28 August 2002. Thereafter at intervals not to exceed 25 hours time in

service.

c. Unless the initial inspection is already accomplished, within 5 hours time in service after 28 August 2002. Thereafter at intervals not to exceed 100 hours time in service.
d. Unless already accomplished, within 300 hours time in service after 28 August 2002 or at the next overhaul, whichever occurs first.

This Amendment becomes effective on 28 August 2002.

Enstrom F-28 Series Helicopters Enstrom F-28 Series Helicopters

Enstrom F-28 Series Helicopters

AD/ENST 28/9 Amdt 4 (continued)

Background: Emergency FAA AD 76-17-08 required repetitive inspections of the shoulder radius of the main rotor shaft.

Amendment 1 reduced the dye-penetrant inspection periods following further investigation by the manufacturer.

Amendment 2 removed from service main rotor shafts not modified in accordance with SDB No. 0036.

Amendment 3 was prompted by the failure of a shaft on a Model F-28A helicopter due to a fatigue crack. This Directive added models previously unaffected, which have a “small radius fillet” main rotor shaft installed.