68-03-01 FAIRCHILD-HILLER: Amdt. 39-547 as amended by Amendment 39-987. Applies to FH-227 Type Aircraft.
Compliance required within the next 5 hours' time in service after the effective date of this AD unless already accomplished within the last 20 hours' time in service and thereafter at intervals not to exceed 25 hours' time in service from the last inspection. The repetitive inspections also apply to repaired and replacement parts.
In view of flutter of the elevator trim tab, accomplish the following:
(a) Inspect the elevator trim tab for trailing edge free play not to exceed 0.100 inch max. travel. Compliance with this limit must be met prior to further flight.
(b) Visually inspect all elevator tab hinge bearings for damage. Replace damaged bearings, prior to further flight, with a part of the same part number that has been inspected in accordance with this directive prior to installation, or with an FAA approved equivalent part.
(c) Visually inspectthe entire elevator tab structure for loose rivets, cracks, or any structural deformation. Prior to further flight, remove and replace loose rivets, replace deformed trim tabs, and repair or replace cracked trim tabs with a part of the same part number that has been inspected in accordance with this directive prior to installation or with an equivalent part or repair approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(d) Inspect the elevator trim tab clevis bolts, elevator trim tab horn, elevator trim tab actuator, rod end and rod assembly rivets, for looseness and damage. Prior to further flight, loose items must be properly secured and damaged parts replaced with a part of the same part number that has been inspected in accordance with this directive prior to installation, or with an FAA approved equivalent part.
(e) Visually inspect the 3 elevator trim tab hinges for elongated holes in the clevis holes of the aluminum blocks located behind the3 elevator trim tab hinges. Replace blocks containing elongated holes prior to further flight with a part of the same part number that has been inspected in accordance with this directive prior to installation, or with an FAA approved equivalent part.
(f) Inspect the elevator trim tab spar area around the 3 hinges for cracks. If cracks are found, prior to further flight, the cracked parts must be repaired in accordance with an FAA approved repair, or replaced with a part of the same part number that has been inspected in accordance with this directive prior to installation, or with an FAA-approved equivalent part.
(g) Cut a one-inch hole in the lower tab skin in line chordwise with the existing access hole in the lower tab skin at tab station 14.662, and located spanwise 11.4 inches outboard of the most inboard tab rib. Fabricate a circular doubler 2 inch O.D. by 1 inch I.D. from 0.025 inch thick 2024T3 alclad material specification QQ-A-250/5. Finish with alodine or anodizeand apply zinc chromate primer to the faying surface only. Install doubler over hole and secure the doubler with six equally spaced MS20600AD4 rivets or use an equivalent method for inspection approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(1) Inspect the tab ribs adjacent to the 3 tab hinges and also the tab ribs supporting the tab horn for cracks paying particular attention to rib flange radii using a borescope or light and mirror through the access holes or use an FAA-approved equivalent inspection method. The x-ray inspection procedure specified in Fairchild Hiller Alert Service Bulletin No. 27-17A (FH-227) Revision 1 dated January 5, 1968, is considered equivalent to the borescope or light and mirror inspection. If cracks are found, prior to further flight, the cracked parts must be repaired in accordance with an FAA approved repair, or replaced with a part of the same part number that has been inspected in accordance with this directive prior to installation or with an FAA-approved equivalent part.
(2) After each inspection, cover the access holes with permacelle tape or equivalent.
(h) For aircraft with a modified elevator trim tab approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, comply with paragraphs (a), (b), (c), and (d), prior to accumulating 600 hours' time in service on the modified tab, and thereafter at intervals not to exceed 600 hours' time from the last inspection. If the inspections of (a), (b), (c), or (d), reveal a discrepancy, then the requirements of paragraphs (e), (f), and (g)(1) and (g) (2), must be complied with prior to further flight.
(i) Equivalent inspections may be approved by an FAA maintenance inspector. Equivalent repairs and parts must be approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(j) Upon request with substantiating data submitted through an FAA maintenance inspector, the compliance times specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
Amendment 39-547 is effective February 2, 1968, for all persons except those to whom it was made effective immediately by telegram dated January 9, 1968.
This Amendment (39-987) is effective May 27, 1970.