Date: 201903
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Pax Seat
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Other / Unknown
Second reporter function: Technician
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General None Reported / Taken
Contributing factors: Incorrect / Not Installed / Unavailable Part; Human Factors; Company Policy; Aircraft; Manuals; Procedure
Primary problem: Procedure

Narrative: I was assigned to Aircraft X; 'Fold down tray tables at over-wing emergency exit rows.' In the process of troubleshooting the issue I verified that the latest seat mod accomplished to the aircraft was [Modification A]. Per [a step in Modification A] 'install new [Brand A] tourist seats IAW (In Accordance With) B737NG [maintenance manual] in locations specified on applicable NAT drawing;' Per [the] drawing the seat part numbers for Emergency Exit rows 14 & 15 are [listed]. I performed an inspection on the seat assemblies installed in those positions and determined that the seat part number are installed in the correct positions per the referenced drawing. The referenced drawings also show that those seats have rear mounted tray tables installed.During my inspection of the documented condition I had several concerns about the safety of the [modification] and its accomplishment instructions. [Modification A] states that the seats should be installed IAW the [maintenance manual] but when I pulled up that reference I did not see any instructions for installing a [Brand A] tourist class seat. There were installation instructions for [other brands of] coach seats and a [Brand A] first class seat.I have questions as to the safety of the aircraft when configured per this [modification]. There is a distinct possibility that in an accident the tray tables can block the emergency exit aisle between rows 14-15 and 15-16 on both the left and right seat rows making the over-wing escape doors unusable. The referenced [maintenance manual] task and the drawing both reference a minimum 13' escape path between the rows 14-15 and 15-16. The [maintenance manual] 'Passenger seat recline restrictions check at emergency exits' instructs to check that the seat backs do not recline into that 13' minimum dimension between seat. I question the concern of having a seat recline restrict that minimum dimension of 13' between seat rows in the emergency exit area but allow a tray table to completely block the emergency aisle path and restrict egress at the emergency exit over wing doors.


Second narrative: I went out to aircraft for an aft lavatory issue. On my way back to the front of the aircraft I noticed a tray table down in the exit row of the aircraft which would prevent ease of exit in the emergency row in case of an emergency event. I called tech services and they said it's not right but the FAA wrote off on it. Normally the tray tables are stored in the armrest. There has been reported findings on all the aircraft [with this modification].I would like clarity if this configuration is proper that tray tables extend into the exit row.


Synopsis: Technician reported that new seats are installed in the exit row on 737NG with Seat Back Tray Tables which could block egress path in violation of FARs.