Airworthiness Directive · Amendment 39-18433 · Stabilizers
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-300, -400, and -500 series airplanes. This AD requires repetitive inspections for cracking in the horizontal and vertical flanges of the rear spar upper chord of the horizontal stabilizer, and related investigative and corrective actions if necessary. This AD was prompted by a report of cracking in the center section of the horizontal stabilizer. We are issuing this AD to detect and correct cracking of the rear spar center section of the horizontal stabilizer that could lead to departure of the horizontal stabilizer from the airplane.
At the applicable times specified in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraphs (j)(1), (j)(2), and (j)(3) of this AD: Do the actions required by paragraph (g)(1) or (g)(2) of this AD; and do all applicable related investigative and corrective actions; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraph (j)(4) of this AD. Do all applicable related investigative and corrective actions at the applicable times specified in tables 5, 6, 7, and 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016. For airplanes on which “Option 1” of “CONDITION 15: SURFACE HFEC INSPECTION OF THE CHORD AROUND THE GUSSETS—NO CRACK FOUND” is done as specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, repeat the inspection specified in paragraph (g)(2) of this AD thereafter at the applicable times specified in table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016.
(1) Do an inspection to identify the fasteners common to the rear spar upper chord upper gusset of the horizontal stabilizer center section.
(2) Do a surface high frequency eddy current (HFEC) inspection of the rear spar upper chord around the two inboard gusset plates common to the thrust and auxiliary beams for any crack.
At the applicable times specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraphs (j)(1) and (j)(2) of this AD: Do a surface HFEC inspection of the vertical flange of the rear spar upper chord; and do all applicable corrective actions; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraph (j)(4) of this AD. Do all applicable corrective actions before further flight. Repeat the inspection of the vertical flange of the rear spar upper chord thereafter at the time specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016.
At the applicable times specified in table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraphs (j)(1) and (j)(2) of this AD: Do the actions required by paragraph (i)(1) or (i)(2) of this AD; and do all applicable related investigative and corrective actions; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, except as required by paragraph (j)(4) of this AD. Do all applicable related investigative and corrective actions at the applicable times specified in tables 3 and 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016. Repeat the inspection specified in paragraph (i)(2) of this AD thereafter at the applicable times specified in tables 3 and 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016.
(1) Do an open hole HFEC inspection of the vertical flange at the stiffeners of the rear spar upper chord on the horizontal stabilizer center section for any crack.
(2) Do a surface HFEC inspection of the vertical flange around the stiffeners of the rear spar upper chord on the horizontal stabilizer center section for any crack.
(1) Where paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, specifies a compliance time “after the original issue date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) Where paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, refers to condition or compliance time in “horizontal stabilizer center section flight cycles” or “center section flight cycles,” this AD requires compliance for those conditions or compliance time in terms of airplane flight cycles.
(3) The Condition column of table 1 in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016, refers to “horizontal stabilizer center section flight cycles.” This AD, however, applies to the airplanes with the specified airplane total flight cycles as of the effective date of this AD.
(4) Where Boeing Alert Service Bulletin 737-55A1100, dated January 26, 2016; specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (k) of this AD.
