Airworthiness Directive · Amendment 39-11908 · Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-120, EMB-120ER, and EMB-120RT Series Airplanes
Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-120, EMB-120ER, and EMB-120RT Series Airplanes
Model EMB-120, EMB-120ER, and EMB-120RT series airplanes; serial numbers 120004 and 120006 through 120321 inclusive; certificated in any category; on which EMBRAER Service Bulletin 120-24-0051, dated March 1, 1994; Revision 1, dated May 5, 1994; Revision 2, dated May 31, 1994; Revision 3, dated November 3, 1994; Revision 4, dated March 8, 1995; or the production equivalent, has been accomplished.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD), applicable to certain EMBRAER Model EMB-120, EMB-120ER, and EMB-120RT series airplanes, that requires removal of a certain fastener, if applicable, and sealing of the corresponding fastener hole. This action is necessary to prevent contact between one of the bolts that attaches the direct current (DC) relay box on the left-hand side of the airplane and one of the power terminals of electrical emergency contactor 2, which could result in a short circuit in the DC relay box, and consequent partial loss of the electrical system, and degraded operation of airplane systems. This action is intended to address the identified unsafe condition.
To prevent contact between one of the bolts that attaches the direct current (DC) relay box on the left-hand (LH) side of the airplane (hereinafter referred to as the “LH DC relay box”) and one of the power terminals of electrical emergency contactor 2 (K0519), which could result in a short circuit in the LH DC relay box, and consequent partial loss of the electrical system, and degraded operation of airplane systems, accomplish the following:
(a) Within 75 flight hours after the effective date of this AD, remove the bolt and washer on the LH DC relay box that is in the area of electrical emergency contactor 2 (K0519) and seal the corresponding fastener hole, in accordance with EMBRAER Alert Service Bulletin 120-24-A057, dated November 14, 1996. If no fastener is installed, seal the corresponding fastener hole only, in accordance with the alert service bulletin.
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.
