Date: 201602
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Wing Leading Edge
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown
Second reporter function: First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: Manuals; Logbook Entry; Procedure; Aircraft
Primary problem: Procedure

Narrative: First Aircraft; FO (First Officer) found dent in leading edge of right wing with very sloppy; conspicuous repair. Noted in the damage log; but looked substandard and damaged.Same plane; FO found undocumented 12 in crack in vapor barrier with very old and peeling speed tape. This crack was open and barrier crack edges were separated. Tape was worn off in parts and crack was visible.  There was no item in the logbook. The crack had propagated upward and inward past the existing; undocumented crack repair. This crack was subsequently after reporting; aircraft was taken out of service; signed off as a new crack.In summation reference this vapor barrier issue; we found undocumented maintenance on an aircraft. We found an aircraft flying in an un-airworthy condition after this undocumented aircraft was repaired and not documented. There is a current airworthiness directive on this subject. I have no idea how long this plane has been flying in this un-airworthy condition.There were RII's (Required Inspection Items) not accomplished on this aircraft. This is documented by me with a post incident review of the [manual].The next aircraft we were given had 2 issues. There was clear Mylar tape on the outside of the R-3 window. It was peeling off. Maintenance wanted to peel tape off and was not happy I requested an investigation. A Log entry was then made. Per another Mechanic; this tape was still required to keep window sealant in place during the cure process. The mechanics later acknowledged that had the tape been in fact peeled off and flown again; since the sealant was still tacky; the window would have been required replacing again.The FO found on this aircraft as well an undocumented repair to the right wheel well vapor barrier. This repair appeared to be in acceptable condition. There was no TAC (Tracking and Control) item for this crack. A later; further inspection of the sign off; showed an incorrect repair reference to the GPM (General Procedures Manual) and not the SRM (Structural Repair Manual) as required; since the vapor barrier is a secondary structural member. An FEA (Fleet Engineering Authorization) was required for this sign off and was not accomplished as far as I could find in my forensic [manual] search.In summation; we found another undocumented repair to another aircraft. This aircraft came out of C-check the day prior. This crack was signed off that same day as a new crack. I found through an [manual] search that there were RII's not accomplished on the aircraft. This crack appeared to be signed off as a new crack without a required FEA. This alarming '2 aircraft in a row' finding; is a grave indication of significant malfeasance in our maintenance department and could or will lead to significant fines and/or hull loss.

Callback: Reporter stated: The dent in the wing was poorly repaired; 'Looks like to was done by some high school kid'.  Reporter also stated: The cracks in the Vapor Barrier is an ongoing issue. The Vapor Barrier is required to be inspected every 600 hours or every 'B' check. These cracks are to be entered in the Track and Control (TAC) system and removed after the repair is accomplished. The reporter stated that the item is often removed before the repair is accomplished. The reported stated that the repairs; when accomplished; are not being repaired per the Structural Repair Manual.  The reporter Stated that he has reported this in the past and that the FAA and Boeing are aware of the cracks in the Vapor Barriers.

Second narrative: [Report narrative contained no additional information.]


Synopsis: A B737-800 had unreported damage to the Leading Edge of the RH wing and some undocumented cracks on the Vapor Barrier in the wheel well area.