Flying the PAC 750XL

The PAC 750XL is a utility aircraft with incredible performance, strength, and capacity.  The 750XL was designed specifically for sky diving but can serve a wide range of duties including freight, passenger operations, photography, or agricultural work.  For hauling jumpers, nothing’s better.  It’s just about the perfect airplane.  It has superb short take off and landing capabilities and the thick cord / high lift wing make getting to altitude with a heavy load of jumpers a snap.  Initial climb rates exceed 2000 ft/min with 700lbs of fuel and 14 jumpers and above 12,000 ft. climb rates will continue to exceed 1000 ft/min.
Here are some of the specs: 

• Pratt & Whitney PT6A-34 750hp engine (4,000hr TBO)
• Pilot + 9 passengers or 17 parachutists
• Maximum take off Weight 7,500 lbs
• Basic Empty Weight 3300 lbs
• Payload 4,200 lbs
• VY 90 kts, Cruise 169 kts
• Typical jump run max fuel load, 850 lbs
• SL to 13500’ and back, fuel burn approx. 100lbs or 14.7 Gal
• Cabin 54 " wide, 56" high and 158" aft of pilot
• 150 hour maintenance cycles
• To 13,500 ft from brake release in under 13 minutes

The PAC 750 XL is a bone simple airplane.  It’s an all metal, riveted, stressed skin construction with a single cantilever low wing and tricycle undercarriage.   (down and welded).  All the flight controls are non boosted manually operated cables, push rods and torque tubes. The cockpit accommodates two pilots side-by-side with access via hinged doors on either side of the cockpit.   It’s nicely equipped with dual Garmin 430’s and full set of EI instruments.

The main cabin/cargo area is roomy and jumpers can sit side by side facing aft on bench type seats.  The wing is the most striking external feature of the airplane that catches everyone’s eye almost immediately.   The wing is basically made up of two sections…outboard and inboard.  Throughout the entire span the wing has a constant chord and a constant aerofoil section.  The inboard section of the wing has no dihedral and the outboard part of the wing has a dihedral angle of 8º.  This combination maximized available lift while maintaining adequate lateral stability.  An incidence angle of 2º is maintained throughout the span.

Single slotted flaps are fitted at the trailing edge of the inboard portion of the wing. Conventional ailerons with balance tabs on both ailerons and an electrically operated trim on the left hand aileron are attached to the outer panels.  Flaps are exceedingly effective and take off are performed with no flaps and landing typically with ½ flaps.

The stability of the A/C, and its’ low speed performance make it a pretty easy to fly.  The CG envelope is “gi-normous” (generous).  If the cabin is full then the jumpers weight is spread out correctly.  If there are only a few jumpers they can literally sit anywhere they want with little or no adverse effects to the CG.  
The passenger/cargo door is located on the left hand side of the fuselage behind the wing trailing edge. The door is approximately 50” wide and 47” high at the front and 41.3” high at the rear.  It slides up into the cabin for ingress or egress and can be opened or closed from both inside and outside.

Take Off and Climb

What surprises you is how fast it’s ready to fly.  If you add the power smoothly, by the time you get to the throttle stop or reach a torque or ITT limit you’ve past lift off speed usually around 65-70 kts. (depending on weight and temp).  With ½ flaps selected, it has none of the unpleasant tenancies that you might associate with a big single engine aircraft.  A little right rudder is all that’s required to keep it tracking straight.   If I had to find fault I’d say that the PAC wants to fly “too soon”.  The best method for achieving a clean crisp take off is to hold slight forward control pressure keeping the nose wheel on the runway until lift off speed is achieved.  Add slight back pressure and it pops off the ground nicely.

Climb out, even with a heavy load is just phenomenal.  The big hartzell prop grabs the air and pulls the aircraft skyward at an amazing rate.  Vx is 80 knots and Vy is 90.  However I’ve found that holding 91-93 knots typically produces a slightly higher rate of climb.  I’m not sure why, but a little faster than book seems to work better on climb out.  With typical loads I’ll see 8000 ft in about 4-6 minutes and 12000 in less than 10 minutes.  Above 10000 ft climb rates are close to 1000 ft/min so it makes the math easy to reach jump altitude (13,500) in most cases and the “spot” at the same time.

Jump Run

The jump run is also fairly straight forward.  Set up the Garmin with the Drop Zone (DZ) coordinates in a user waypoint; select direct to the DZ and use the OBS function to set up the run in line.  The GPS shows time, speed, distance and cross track error.  All the pilot has to do is make small timing corrections for whatever DME offset the jumpmaster and pilot agree on.

Aircraft configuration is also pretty simple.  Arrive at the drop point with about 80-85 knots KIAS, ½ flaps and 30 lbs of torque to hold altitude.  When it’s time for the green light to come on, bring the power back to 15 lbs of torque and the prop back to 1880 rpm.  Allow the plane to slow then descend to maintain airspeed between 70-80 knots.  This configuration and airspeed make the exit comfortable for the jumpers, especially if there are 4-ways that have to hang outside for awhile.
As the jumpers leave there will be a slight forward pitch as the weight in the back suddenly disappears.  It’s very controllable with just a slight amount of trim or aft stick pressure.  After everyone is out pull the handle above the pilots head to close the door, raise the flaps, turn off the jump lights, go to idle power and prop where it was for the descent. 

Descent

Idle power and 1880 on the RPM’s to keep the noise of the prop down.  If you run the prop faster, you’ll make one heck of a racket on the ground and the locals will probably call to complain.  This configuration and 130-140 knots will keep you well within the green arc and coming down at a respectable 3000-4000 ft/min. 
To keep the boss happy idle descents to touchdown are the goal.  It uses less gas and builds dead-stick skills rather quickly.  A good rule of thumb for pattern is to be at about 4000 ft on a mid field downwind and 2000 ft for the turn to base.  After that I just eyeball the landing using ½ flaps and point the nose 200-300 yards short of the runway threshold.  This usually yields about an 85-90 knot approach speed.  This is about 30 knots above touch down speed.  That’s why you’ll need to point the nose at the grass short of the runway.  Use the round out to the flare to bleed off excess speed and touchdown on the first 500 ft of paved runway.  Once you begin to round out the descent and start your flare airspeed decays rapidly.  Make sure you’re over pavement with the wheels just a few inches off when the airplane quits flying.  Post landing checks are simple.  Leave the flaps alone because you’ll need the ½ position for the next take off and reset the trim.
 
Try to keep fuel levels between 850 lbs max and 250 lbs min.  This gives you enough fuel for 6 loads without having to get gas while at the same time keeping the Wt & Balance well inside the envelope.

This write up has been provided by George Merle. He has over 4,000 hours flying experience with most of it in F-18 and F-14 aircraft as a Naval Aviator. He has an ATP and CFII and currently flys for Skydive Suffolk in Virginia which was the first US DZ to purchase a PAC 750XL. Thank you George for your service to our country and your contribution to this site. -Chris Schindler