Cessna 172M Skyhawk (1973-1976)

The 1973-1976 Cessna 172M is the most-produced single variant in the 1968-1976 Lycoming 150 HP era -- approximately 6,825 examples built across four model years, accounting for over a third of all 150 HP Lycoming 172 production. Its defining feature is the Camber-Lift wing with a slight drooped leading edge that improved low-speed handling, increased aileron authority near the stall, and reduced takeoff distance. A baggage door also became standard (previously optional). Combined with the tubular gear inherited from the 172L and the standard interior of the 172K, the 172M represents the most refined 150 HP 172 before the 160 HP era began with the 172N.

For buyers seeking a 150 HP 172, the 172M is the clear preferred choice over the 172I/K/L when budget allows. The Camber-Lift wing makes the airplane noticeably more docile in slow flight, and the standard baggage door is a meaningful convenience.

Standard Baggage Door

The 172L (and earlier) required all baggage to be loaded through the right cabin door, then passed back to the baggage compartment. The 172M's standard baggage door (on the right side of the fuselage behind the rear seats) allows direct loading from outside. This is a major convenience for cross-country flying with luggage and is one of the reasons the 172M is preferred over the 172L for serious touring use.

Distinguishing Features (vs 172L and 172N)

The Camber-Lift Wing

The Camber-Lift modification introduced in 1973 added a slight downward curvature to the leading edge of the wing inboard of the strut attach point. The change is visually subtle -- you have to know what to look for -- but the aerodynamic effect is meaningful:

• Lower stall speed: Roughly 1-2 knots reduction in stall speed (Vs0 ~40 KIAS)
• Improved aileron authority near the stall: The drooped leading edge keeps inboard wing sections flying at higher AOA, leaving outboard ailerons effective
• Better low-speed handling: More docile behavior in slow flight and approach configurations
• Shorter takeoff distance: Slight improvement (~50-100 ft) at typical operating weights

The Camber-Lift design became standard on all subsequent 172s through 1986 and remained on the post-1996 restart 172R/172S. It is one of the more impactful wing aerodynamic refinements in 172 history.

Comparison: 172M vs 172N vs 172P

122 KTAS cruise, 645 FPM climb, 8.0 GPH. The Camber-Lift wing adds approximately 1 KTAS cruise vs the 172L due to better leading-edge airflow. Useful load: ~920 lbs (the highest of the 1968-1976 Lycoming era due to slightly lower empty weight relative to the L).

Identical to 172I/K/L. See cessna-172i for engine details. The 172M is the last 172 with the O-320-E2D; the 172N (1977) introduced the troublesome O-320-H2AD that prompted the famous "Operation Blue Streak" remediation program.

The 172M typically commands $3,000-$8,000 over a 172L in equivalent condition. Restored 172Ms with modern panels often exceed $90,000 -- approaching the price of a 172N (which has its engine-related questions) or a 172P (which is mechanically preferable but pricier). The 172M-172P spread is the central "what mid-era 172 should I buy" decision.

Universal Cessna 172 pre-buy concerns apply. 172M-specific:

1. Wing leading edge inspection: The Camber-Lift drooped leading edge can be damaged by hangar rash or ramp incidents. Inspect for dents or repairs.
2. Baggage door seals: Original 1973-1976 baggage door seals are likely dry. Water intrusion through poor seals causes corrosion in the baggage compartment floor.
3. Camber-Lift documentation: Verify the airplane has the factory Camber-Lift wing (some 1973 early-production airframes may have been pre-Camber-Lift; check the type data plate).
4. Engine cam/lifter condition: Although the 172M's E2D is generally reliable, a 50-year-old engine deserves an oil filter inspection and (ideally) borescope inspection.