Airworthiness Directive · Amendment 39-11515 · McDonnell Douglas Model MD-90 Series Airplanes
McDonnell Douglas Model MD-90 Series Airplanes
Model MD-90 series airplanes, as listed in McDonnell Douglas Service Bulletin MD90-53-004, dated August 20, 1998, certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 McDonnell Douglas Model MD-90 series airplanes, that requires a one-time detailed visual inspection to detect fatigue cracking of certain longerons and the attaching frames of the lower left nose; and repair, if necessary. This amendment also requires installation of a preventive modification. This amendment is prompted by several reports of fatigue cracking of certain longerons and the attaching frames. The actions specified by this AD are intended to prevent such fatigue cracking, which could result in reduced structural integrity of the fuselage, and consequent loss of pressurization of the airplane.
To prevent fatigue cracking of longerons 22 through 26 and the attaching frames, which could result in reduced structural integrity of the fuselage, and consequent loss of pressurization of the airplane, accomplish the following:
(a) Prior to the accumulation of 40,000 total landings, or within 24 months after the effective date of this AD, whichever occurs later: Perform a detailed visual inspection to detect cracking of longerons 22 through 26 (inclusive) and the respective attaching frames at station frames Y=160.000 and Y=200.000 of the left lower nose, in accordance with McDonnell Douglas Service Bulletin MD90-53-004, dated August 20, 1998.
Note 2: For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
(1) If no cracking is detected: Prior to further flight, install clips and doublers under the longeron flanges and shim the longerons in accordance with the service bulletin.
(2) If any cracking is detected: Prior to further flight, repair the cracks and install clips and doublers under the longeron flanges and shim the longerons in accordance with the service bulletin.
