Airworthiness Directive · Amendment 39-15059 · Enstrom Helicopter Corporation Model F-28A, F-28C, F-28F, TH-28, 280, 280C, 280F, 280FX, 480, and 480B Helicopters
Enstrom Helicopter Corporation Model F-28A, F-28C, F-28F, TH-28, 280, 280C, 280F, 280FX, 480, and 480B Helicopters
Model F-28A, F-28C, and F-28F helicopters, excluding serial number (S/N) 816 and subsequent; Model 280, 280C, 280F, and 280FX helicopters, excluding S/N 2100 and subsequent; and Model TH-28, 480, and 480B helicopters, excluding S/N 5058 and subsequent, certificated in any category.
This amendment adopts a new airworthiness directive (AD) for Enstrom Helicopter Corporation (Enstrom) Model F-28A, F-28C, F-28F, TH- 28, 280, 280C, 280F, 280FX, 480, and 480B helicopters that requires determining the installation dates for each main rotor push-pull control rod (push-pull rod), inspecting the push-pull rods for corrosion, replacing any push-pull rod which has corrosion that is severe enough to cause pitting, or has visible moisture inside the rod, and repairing each push-pull rod that has corrosion but no pitting. This amendment is prompted by one reported incident in which the helicopter pilot encountered severe in-flight vibration due to the failure of a push-pull rod, requiring an emergency landing. The actions specified by this AD are intended to detect corrosion and prevent failure of a push-pull rod, and subsequent loss of control of the helicopter.
To detect corrosion and prevent failure of a main rotor push-pull control rod (push-pull rod), and subsequent loss of control of the helicopter, accomplish the following:
(a) Within 10 hours time-in-service (TIS) or at the next annual inspection, whichever occurs first, review the helicopter maintenance records and determine the date that each push-pull rod, part number (P/N) 28-16253—all dash numbers (for Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters) and P/N 4140532—all dash numbers (for Model TH-28, 480, and 480B helicopters), was installed. If the date cannot be determined from the maintenance records, use the “Date MFD”, which is located on the helicopter data plate, as the installation date for the push-pull rod.
(b) For Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters, using the compliance times stated in Table 1 of this AD, visually inspect the exterior and interior of each of the three push-pull rods for corrosion severe enough to cause pitting or any moisture, paying special attention to the area of the lower fitting, in accordance with section 5.1., INSPECTION, in Enstrom Helicopter Corporation Service Directive Bulletin No. 0096, dated September 10, 2003 (SDB 0096).
| Helicopter models | Push-pull rod service life | Compliance times |
|---|---|---|
| Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters | Push-pull rod that has been installed for 20 or more years | Inspect within 10 hours time-in-service (TIS) or at next annual inspection, whichever occurs first. |
| Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters | Push-pull rod that has been installed for 10 or more years, but less than 20 years | Inspect within 50 hours TIS or at the next annual inspection, whichever occurs first. |
| Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters | Push-pull rod that has been installed for less than 10 years | Inspect before the service life of the push-pull rod reaches 10 years since initial installation. |
(1) Before further flight, if corrosion without pitting is found on a push-pull rod, then repair, reassemble, remark, and reinstall it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB 0096.
(2) Before further flight, if corrosion is found that is severe enough to cause pitting, or if any moisture is visible on the inside of a push-pull rod, replace it with an airworthy push-pull rod.
Note 1: Determining continued serviceability of the push-pull rods by inspecting the exterior only of each push-pull rod is described in Enstrom Helicopter Corporation Service Information Letter No. 0156, dated December 9, 2003.
(c) For Model TH-28, 480 and 480B helicopters, using the compliance times stated in Table 2 of this AD, visually inspect the exterior and interior of each of the three push-pull rods for corrosion severe enough to cause pitting or any moisture, paying special attention to the area of the lower fitting, in accordance with section 5.1., INSPECTION, in Enstrom Helicopter Corporation Service Directive Bulletin No. T-019, dated September 10, 2003 (SDB T-019).
| Helicopter models | Push-pull rod service life | Compliance times |
|---|---|---|
| Model TH-28, 480, and 480B helicopters | Push-pull rod that has been installed for 10 or more years | Inspect within 50 hours TIS or at the next annual inspection, whichever occurs first. |
| Model TH-28, 480, and 480B helicopters | Push-pull rod that has been installed for less than 10 years | Inspect before the service life of the push-pull rod reaches 10 years since initial installation. |
(1) Before further flight, if corrosion without pitting is found on a push-pull rod, then repair, reassemble, remark, and reinstall it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB T-019.
(2) Before further flight, if corrosion is found that is severe enough to cause pitting, or if any moisture is visible on the inside of a push-pull rod, replace it with an airworthy push-pull rod.
Note 2: Determining continued serviceability of the push-pull rods by inspecting the exterior only of each push-pull rod is described in Enstrom Helicopter Corporation Service Information Letter No. T-019, dated December 9, 2003.
(d) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Chicago Aircraft Certification Office, Small Airplane Directorate, FAA, for information about previously approved alternative methods of compliance.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
