David Learmount/LONDON
Embraer has issued urgent instructions to ERJ-145 pilots about how to cope with a pitch trim which is liable to jam soon after take-off. On 19 January, the US Federal Aviation Administration made the instructions mandatory for US operators by issuing an emergency airworthiness directive (EAD).
The EAD, a slight variation on Embraer's Alert Service Bulletin issued to operators on 8 January, demands that placards on the instrument panel and amendments to the Aircraft Flight Manual give the pilots information on how to avoid pitch trim jam and how to overcome it if it occurs.
The EAD does not require any modification to the aircraft, but Embraer says that it is working on a solution in the medium term.
The cockpit placard required by the EAD reminds pilots that the maximum airspeed after take-off or during climb without re-trimming is 160kt (296km/h) indicated airspeed (IAS). Compliance was required by 22 January. If the pilot allows the aircraft to accelerate through 160kt IAS before applying any nose-down trim, the load on the horizontal stabiliser actuator becomes too great for it to operate, so the pitch trim is effectively jammed.
Ten 10 occurrences have been reported in the USA, according to the FAA, and at least one full emergency has been declared in the UK. This temporary pitch trim jam can be overcome by reducing the IAS below160kt to reduce the stabiliser load, and re-trimming before accelerating again.
Source: Flight International
