80-16-03 LET BLANIK: Amendment 39-3861. Applies to Model L 13 gliders, certificated in all categories.
Compliance required as indicated.
To prevent failure of the horizontal stabilizer outer end ribs, accomplish the following:
(a) Within the next 10 hours time in service after the effective date of this AD, visually inspect the radii of the horizontal stabilizer end ribs for cracks in accordance with paragraph A, "Inspection," LET Mandatory Bulletin No. L 13/052, not dated, or an FAA- approved equivalent.
(1) If, during this inspection no cracks are found on either rib, before further flight, unless already accomplished, reinforce the stabilizer end ribs in accordance with paragraph B, "Reinforcement of stabilizer end rib," LET Mandatory Bulletin L 13/052, not dated, or an FAA-approved equivalent, at which time no further action is required by this AD.
(2) If, during this inspection cracks are found and the total crack length on either rib exceeds 10 mm,before further flight, replace both ribs (except that a crack-free rib need not be replaced) with new ribs of the same part number in accordance with paragraph C, "Replacement of stabilizer end rib," LET Mandatory Bulletin No. L 13/052, not dated, or an FAA-approved equivalent, and reinforce both ribs in accordance with paragraph B, "Reinforcement of stabilizer end rib," LET Mandatory Bulletin No. L 13/052, not dated, or an FAA-approved equivalent, at which time no further action is required by this AD.
(3) If, during this inspection any cracks are found but the total crack length on each rib does not exceed 10 mm -
(i) Before further flight, replace and reinforce stabilizer end ribs in accordance with paragraph (a)(2) of this AD at which time no further action is required by this AD; or
(ii) Accomplish the following:
(A) Before further flight, unless already accomplished, repair all cracks and reinforce both ribs in accordance with paragraph B, "Reinforcement of stabilizer end rib," LET Mandatory Bulletin No. L 13/052, not dated, or an FAA-approved equivalent; and
(B) At intervals not to exceed 100 hours time in service from the last inspection, visually inspect the radii of the horizontal stabilizer outer end ribs in accordance with the method specified in paragraph (a) of this AD.
(b) If, during any of these repetitive inspections accomplished in accordance with paragraph (a)(3)(ii)(B) of this AD any further cracking is found on either rib, replace both ribs (except that a crack-free rib need not be replaced) with new ribs of the same part number and reinforce any replacement ribs in accordance with the methods specified in paragraph (a)(2) of this AD, at which time no further action is required by this AD.
(c) For those gliders on which the stabilizer end ribs were reinforced in accordance with LET Mandatory Bulletin No. L 13/042, dated August 16, 1976, or an FAA-approved equivalent, comply with paragraph (a) of this AD.
(1) If no cracks are found during the inspection required by paragraph (a) of this AD, no further action is required by this AD.
(2) If any cracks are found during the inspection required by paragraph (a) of the AD, replace both ribs (except that a crack-free rib need not be replaced) with new ribs of the same part number and reinforce any replacement ribs in accordance with the methods specified in paragraph (a)(2) of this AD at which time no further action is required by this AD.
(d) For the purpose of this AD, "total crack length" means the combined length of all cracks on a rib, including those cracks already repaired.
(e) For the purpose of this AD, an FAA-approved equivalent may be approved by the Chief, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Office, Federal Aviation Administration, c/o American Embassy, Brussels, Belgium.
NOTE: Cracks in the horizontal stabilizer end ribs may be caused by failure to protect critical parts of the glider during ground transportation or hand assembly or disassembly.
This amendment becomes effective August 11, 1980.