Walkaround

Boeing

737 NG

737-600, -700, -800, -900ER

in service CFM56-7B 3 min read · updated 21 September 2026 · checked 21 September 2026

At a glance

Type card

Variants737-600, 737-700, 737-800, 737-900ER
EnginesCFM International CFM56-7B
Typical seating110 to 180
StatusOut of production, in widespread service
Produced1997 to 2019, roughly 7,000 aircraft
Successor737 MAX

Program and production

Production ended in 2019 and the programme is now entirely an in service and aftermarket story. That does not make it small. With roughly 7,000 aircraft built, the NG is still the backbone of short haul flying worldwide, and it will remain so for years given how slowly MAX deliveries are arriving.

The most consequential programme dynamic is indirect. Every month Boeing fails to stabilise MAX output at 47 per month is a month operators keep NG airframes flying past the retirement date they had planned. That pushes maintenance spend into airframes originally scheduled to leave the fleet, and it sustains demand for parts and engine overhaul capacity that the market is already struggling to supply.

Passenger to freighter conversion continues to take mid life 737-800 airframes out of the passenger market. The 737-800BCF and competing conversion programmes have given the type a second career, which supports residual values and keeps used airframes scarce.

Technical and maintenance

The structural item worth your attention is the bear strap cracking at the forward galley door cutout.

In plain terms

A bear strap is a reinforcing strip around a fuselage cutout. Cutting a door into the skin interrupts the load path, and the bear strap carries that load around the opening. Cracking there is a primary structure concern, not a cosmetic one.

This cracking was first reported on the NG fleet. The FAA's August 2026 directive against the MAX family, covering 471 US registered aircraft and about 1,429 worldwide, was issued precisely because the MAX shares the NG fuselage design and assembly process. In other words, the MAX inspection campaign exists because of what operators found on NG airframes.

If you work a mixed NG and MAX fleet, that shared lineage is the practical point. The inspection technique, the repair history question and the on condition actions are closely related across both families.

On the line

Pull maintenance records for any existing repair in the forward galley door region before scheduling the inspection. A previous repair changes what the task asks for and can change the interval. On high cycle NG airframes, particularly short sector 737-800s, the forward fuselage deserves attention at the next scheduled opportunity rather than at the outer limit.

Separately, the FAA continues to require repetitive inspections of the fuselage skin and structure around the aft drain mast for cracking and corrosion. That directive covers the earlier 737 Classic series rather than the NG, but the same drain mast corrosion mechanism is familiar to anyone who has worked the lower fuselage on ageing narrowbodies.

On the powerplant side, the CFM56-7B is in a demand squeeze. Industry reporting on engine stand utilisation in 2026 puts the CFM56-7B, CFM56-5A and 5B, and the V2500 at the centre of shop visit demand, driven by ageing fleets and the complexity of the work. Stand availability and slot scheduling are real constraints, and turn times reflect that. Plan removals earlier than historical norms would suggest.

Orders and operators

The NG has no order book. What matters instead is the shape of the in service fleet.

CFM56 powered flights have fallen from about 43 percent of A320 and 737 family activity in 2024 to around 42 percent in 2026, a slow decline that reflects fleet renewal rather than collapse. The comparison is a useful reality check against the assumption that the previous generation narrowbody is disappearing quickly. It is not.

Southwest, Ryanair, American, United and Delta remain the largest operators of the 737-700 and 737-800 in the United States and Europe. Lessors continue to place mid life NG airframes with operators in markets where new delivery slots are simply unavailable before the 2030s.

Safety

No significant developments since 21 September 2026.

The bear strap cracking is being managed through continued airworthiness action rather than accident investigation. No NG hull loss or serious incident opened a new investigation in this period.

Sources