Airworthiness Directive · Amendment 39-16942 · Engine controls
Eurocopter Deutschland Model EC135 Helicopters
This AD applies to Model EC135 helicopters with Turbomeca Arrius 2B or 2B1 engines installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Eurocopter Deutschland (ECD) Model EC135 helicopters. This AD results from a mandatory continuing airworthiness information (MCAI) AD issued by the aviation authority of the Federal Republic of Germany, with which we have a bilateral agreement, to identify and correct an unsafe condition. The MCAI AD states that in the past, the FADEC FAIL caution light illuminated on a few EC135 T1 helicopters. It states that this was caused by a discrepancy in the parameters that was generated within the fuel main metering unit and transmitted to the FADEC. This discrepancy led to the display of the FADEC FAIL caution light and "freezing" of the fuel main metering valve at its position, resulting in loss of the automatic engine control in the affected system. With the MCAI AD, a synchronization procedure for pilots, which was already used in the past, is being reintroduced, which prevents the parameter discrepancy arising and thus sustains the automatic engine control. The AD actions are intended to prevent failure of the FADEC to automatically meter fuel, indicated by a FADEC FAIL cockpit caution light, and subsequent loss of control of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
Within 50 hours time-in-service (TIS), either insert the following procedure by making pen-and-ink changes to the Rotorcraft Flight Manual (RFM) or by inserting a copy of this AD into the Limitations Section of the RFM.
SPECIAL INFORMATION FOR OEI/AUTOROTATION TRAINING AND APPROACH/LANDING PREPARATION
In order to prevent a malfunction, which could lead to a FADEC FAIL indication, the following procedure is mandatory:
The procedure shown below must be performed while in a steady flight condition and at a safe altitude:
—Before initiation of every approach (with or without landing)
—During training of OEI or Autorotation before every switch-over to IDLE
CAUTION: DURING THE RESET PROCEDURE DESCRIBED IN THE FOLLOWING, NO INPUTS ARE TO BE MADE TO THE COLLECTIVE LEVER OR TO THE TWIST GRIP FOR MANUAL ENGINE CONTROL, SINCE THIS CAN LEAD TO AN INEFFECTIVE SYNCHRONIZATION.
The reset procedure is identical for each of two systems and is to be applied for both engines, one after the other.
Procedure
1. ENG MODE SEL switch—Set from NORM TO MAN
After illumination of the ENG MANUAL caution:
2. ENG MODE SEL switch—Set from MAN to NORM: ENG MANUAL caution must go off
Repeat procedure for second engine.
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.
