AD 83-14-09 ACTIVE

83-14-09 EMBRAER: Amendment 39-4692. Applies to Models EMB-110P1 and EMB-110P2 (S/N 110001 through 110386, 110388 through 110397, 110399 through 110401, 110404 through 110408, 110410 through 110412, 110414, 110415 and 110421) airplanes certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To preclude structural failure of the horizontal stabilizer front attachment and fuselage bulkhead 33, accomplish the following:

a) Within the next 50 hours time-in-service after the effective date of this AD, and thereafter at intervals not to exceed 500 hours time-in-service, except as provided in paragraph b) of this AD, visually inspect:

1) The rivets (MS20470AD4) that attach the "C" channels (P/N 4A-1419- 05/06/07/08) to the upper and lower flanges of the "U" shaped machined parts (P/N 4A-1411-07- 16/17) for looseness (see Figure 2, EMBRAER Service Bulletin ((SB)) No. 110-53-019, hereinafter referred to as the SB).

2) The rivets (MS20470AD3) that attach the fuselage skin to the "C" channels described in paragraph a) 1) above and the two lower adjacent channels for looseness (see Figure 3 of the SB).

3) The web or flange areas of bulkhead 33 adjacent to the horizontal stabilizer front fittings, at each side of the fuselage for cracks (see Figure 2, Section C-C of the SB).

b) If loose rivets are found during any inspection required by paragraph a)1) above, in either the upper or lower "C" channel attachments, repeat the inspections in paragraph a) of the AD at intervals not to exceed 125 hours time-in-service until not more than 500 hours time-in- service is accumulated, at which time replace all five rivets (MS20470AD4) in the flange having the loose rivets with Hi-Lock rivets HL-22-77-5-4 or AN3-5A bolts. If loose rivets are found during any inspection required by paragraph a) 2) above, in both the upper and lower "C" channels, prior to further flight replace the rivets. The detailed rivet replacement is shown in Figure 3 of the SB. Accomplish the repetitive inspections of those flanges in which rivets have been replaced at intervals not to exceed 500 hours time-in-service until the "C" channel attachments are reinforced in accordance with the procedures shown in Figure 4 of the SB.

c) If cracks are found during any inspection required by paragraph a)3) of this AD, accomplish the following:

1) If cracks are less than 3 inches, repeat the repetitive visual inspections at intervals not to exceed 125 hours time-in-service until not more than 1000 hours time-in-service is accumulated, at which time repair bulkhead 33 in accordance with Figure 5 of the SB, reinforce the "C" channel attachments, and replace the rivets of the horizontal stabilizer front attachment structure in accordance with Figure 4 of the SB if not previously accomplished. If possible, stop drill the crack ends.

2) If cracks are 3 inches or longer, prior to further flight, repair bulkhead 33web in accordance with Figure 5 of the SB, reinforce the "C" channel attachments, and replace the rivets of the horizontal stabilizer front attachment structure in accordance with Figure 4 of the SB.

3) If the horizontal stablilizer forward attachment fitting (P/N 110-1411-07- 29) rides on the corner of the reinforcing plate (P/N 4A-1419-09), remove excess material from the upper inboard corner of the reinforcing plate (P/N 4A-1419-09), to provide for a proper fit.

d) If no cracks are found in the bulkhead 33 web during any inspection required by paragraph a)3) of this AD, the repetitive inspections of that paragraph are no longer required when the "C" channel attachments are reinforced and the rivets of the horizontal stabilizer front attachment are replaced in accordance with the procedures shown on Figure 4 of the SB.

e) The repetitive inspections required by paragraphs b) and c) of this AD are no longer required when the bulkhead 33 web is repaired in accordance with Figure 5 of the SB and the "C" channel attachments are reinforced and the horizontal stabilizer front attachment rivets are replaced in accordance with Figure 4 of the SB.

f) The intervals between the repetitive inspections required by this AD may be adjusted up to 10 percent of the specified interval to allow accomplishing these inspections concurrent with other scheduled maintenance of the airplane.

g) Aircraft may be flown in accordance with FAR 21.197 to a location where this (AD) can be accomplished.

h) An equivalent method of compliance with this AD may be used if approved by the Manager, Atlanta Aircraft Certification Office, ACE-115A, 1075 Inner Loop Road, College Park, Georgia 30337; telephone (404) 763-7428.

This amendment becomes effective July 27, 1983.