• Throttle Splits - Keep It Comfortable
• Keep Your CF34 Breathing Healthy

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Throttle Splits - Keep It Comfortable

— Bill Walker

A common sight for a repair station is a Challenger aircraft with either a throttle split or an N2 RPM split. Fixing an N2 split results in a more comfortable flight for the passengers and crew. A throttle split and an N2 split should never be confused. An N2 split should only be done by a trained technician with proper equipment.

A throttle split can be checked on the ground, but ideally it is checked in flight by the crew. Properly done, the throttles should go up together or down together to the desired N1 RPM. While adjusting either throttle to obtain 85% N1, do not change directions to get the RPM. If the RPM is overshot, start again by moving the throttles together and resetting N1 RPM to 85%. Then note the exact throttle position and which throttle is leading. This information will help technicians make an accurate adjustment at the throttle gearbox. Here are some tips to follow when making this adjustment. First, the basic throttle rigging should be in accordance with Canadair Maintenance Manual. Second, when making the adjustment, lengthen the leading throttle or shorten the lagging throttle. Next, after the final adjustment, you should feel a cushion or a spring back with the throttle in the cutoff position. This will ensure that you have a positive cutoff when you shut the engine down. Finally, before you safety your adjustments, run the throttle through and verify by the index marks on the fuel control and on the quadrant that the throttles make full travel.

The crew and technicians need to keep each other informed as it may take a flight or two to get throttle adjustments perfect. Duncan Aviation is factory trained and experienced in repairing this as well as N2 RPM split problems. For any questions concerning your CF34 engine, contact Bill Walker or Gerry Riffle at 800.228.4277.

Keep Your CF34 Breathing Healthy

— Bill Walker

As we come out of winter, consider some preventative maintenance to keep your CF34 running cool. De-icing fluid may have been ingested into the engine which you have not had an opportunity to water wash or at least clean the fan assembly and inlets. For operators who do not do water washes in-house, put on rain gear, face shield and gloves and spend a few hours of quality time with your cowlings open. Until your scheduled 300 or 400 hr. inspection for a full water wash, this will keep the dust and other small particles sliding through the fan rather than sticking to it.

Install an inlet cover over the core inlet. Pre-mix B&B 3100 soap with water per the General Electric Maintenance Manual SEI 580 or 780, cleaning section. Adhere to all precautions for handling cleaning chemicals. Sit in the inlet with rags and a soft bristle brush, and thoroughly clean the fan blades, stators, the inner fan support, the forward and aft fan cases and the inlet.With a water hose, thoroughly rinse the fan and inlet and then damp dry the area and squeegee. On the exterior of the engine, use a bug sprayer to spray the wash solution over the engine and then rinse with water. Some areas may require elbow grease, in particular the leading edge of the core cowlings where the grime gets trapped in the S.A.M. holes. Use an airhose with 30 psi pressure to dry the engine.

B&B3100 is the preferred soap but there are alternates listed in General Electric Maintenance Manuals SEI 580 and 780. A bug sprayer can be purchased at any lawn and garden store.

This practice can be used between scheduled water washes and for operators who base their aircraft or fly in and around polluted areas. This includes areas where sand will accumulate under the cowlings.

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