2011-11 · NASA ASRS report 980911
Two pilots report finding several B737-800 NextGen aircraft with lower fuselage body and wheel well fairings cracking in the vertical web sections that support the left and right main wheel well vapor barrier blade seals. The blade seals are attached to the fiberglass fairing on the inside area of each wheel well opening.
November 2011; just picked up a B737-800 aircraft in ZZZ [with a] right wheel well vapor barrier crack placarded in the logbook in August 2011. Went to inspect and found a longer crack (approximately 18 inches) speed taped. [There was] a six inch piece of speed tape coming off and crack progression beyond top of speed tape. Called ZZZ Contract Maintenance (took 30-minutes to get to airport) and gave heads up to Maintenance Control. Maintenance Control noted their records only showed a 6 inch crack. Logbook only went back to November. Sometime between August and November 2011; crack grew 12 inches and was speed taped (no one informed Maintenance Control). ZZZ Contract Maintenance said he almost took plane out of service because it is very difficult to tell cracking paint from cracking fiberglass. Informed Maintenance Control that pearl paint needed to be removed near cracks to visually see cracks. This aircraft was stop drilled previously; but didn't prevent growth of crack. He also told Maintenance Control the plane needed to be inspected on arrival in ZZZ1; not quick turned to ZZZ2.
First; a little bit of history of this November 2011 sequence. I was assigned a B737-800; Aircraft X. I had a conversation with a First Officer (FO) who had this aircraft a few days prior in ZZZ. He indicated a rather large crack in the left wheel well was found during the preflight. The First Officer indicated there was not speed tape applied to this crack and he assumed; based on conversations with Maintenance Control and a Contract Mechanic; that all was good to go. I advised him otherwise. I also noted that the normally required engineering callout number was not issued for this particular repair. Now; fast forward to November 2011; Aircraft X. I saw at sign-in that there was still no engineering callout number issued and spoke with Maintenance Controller X. He explained in great detail as to how this could happen; legally; but he said that he and all his peers always issue an engineering callout for Maintenance notification during Periodic Service (PS) checks and for crew to [be] advised there is speed tape applied. I had this conversation with Maintenance Controller X as I was walking to the gate and he advised he was calling to have an engineering callout issued. NOTE: This crack was first found on or around May 2011 and was improperly signed-off using reference company repair document 57-10-10. The correct reference is Structural Repair Manual (SRM) 57-10-10.I advised the First Officer of the issue and asked him how things looked in the wheel wells. He replied they were clean; as in physically clean and lacking any speed tape. As one who has read the applicable sections of the SRM; I was well aware of the need for a more permanent repair with glass cloth and sealant or a temporary repair consisting of speed tape. So; I inspected the wheel well for myself and found no tape whatsoever. I also found several grease pencil marks that appeared to be rather aged in the vicinity of the repair in question. At that time I made a logbook entry and advised Maintenance Control. Please note; I made a pilot report noting that left wheel well vapor barrier crack has not been properly repaired with speed tape per SRM chapter 57. I specifically asked for a Maintenance Manager due to what appeared to be an improper repair and one arrived. He took Aircraft X out of service due to complications with the paperwork.Next aircraft was Aircraft Y; another B737-800. This aircraft had the proper engineering repair callout and speed tape applied. There was; unfortunately; a further crack progression outside of this taped area that required another sign-off. This one was particularly difficult; since some of the crack was paint cracking and some was actual barrier crack progression. My point; now; is to describe how aware I am of Aircraft Z's issue; as well as my First Officer. We were assigned Aircraft Z in ZZZ1 for the flight to ZZZ2. FO accomplished that walk around and I specifically asked him if he saw any cracks or speed tape; as I advised him there was no aircraft history stating such. He replied there were no indications of vapor barrier cracking. Please note that the FO found the cracks in Aircraft Y; our previous aircraft; as demonstrated by his keen walk around skills and awareness of this issue.November morning; I volunteered to accomplish the walk around. I almost missed the area in question; since this improper repair was covered in PRC or Proseal; a dark grey flexible epoxy based putty [sealant]. What actually caught my eye was the sunrise sunlight reflecting off of what appeared to be a very unsightly crooked line of Proseal. I investigated further and saw obvious cracks; three in total; up to approximately 20 inches; showing in the Proseal. The crack edges were displaced sufficiently to see a shadow as one could almost see into the bay on the other side of the vapor barrier. Curious; I looked closer and saw that there was obviously no fiberglass material inlaid into the PRC. Also; it was obvious that if there was in fact fiberglass; it had at least been torn in the area in question; thereby voiding any repair. Before I called Maintenance; I easily scraped an edge of the very sloppy repair with my fingernail to see if I could feel the evidence of fiberglass tape. I also noted that the required 1-1.5 inch minimum margin for repair required on either side of the crack was blatantly not followed; even if in fact there was fiberglass laid in the PRC.I then called Contract Maintenance and Contract Technician X came to the aircraft. He scraped further with his fingernail and observed several removed pieces to look for evidence of fiberglass material. He observed none. He then spoke with Maintenance Controller Y. Controller Y wanted to know if the crack was all the way through the vapor barrier. Technician X then came back to the Aircraft Z and advised me of the Controller's request. I pointed out to him the obvious areas of splitting and through-barrier cracking. Technician X indicated he wanted to ensure the 'through' cracking. I said; 'What about if you softly push something into the crack to ensure it is in fact not sealed;' and he said; 'Absolutely.' Technician X said he wanted to procure a putty knife to check the splitting; as well as aid in further inspection of crack progression. I suggested possibly a knife from the aircraft to save time and he concurred. I procured a knife and handed it to him. He gently; easily slid the knife into the crack. Technician X wanted to ensure proof of the through-nature of the crack to Controller Y. I would like to say again; this split/crack/opening was already occurring in the PRC sealant prior to any poking by Technician X. Suggest awareness to flight crew and Maintenance about this issue.
More incidents for this aircraft family
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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