Seminole Systems Packet

performance. An important technique is to establish a Zero Sideslip Condition. Sideslip Condition When an engine failure occurs, thrust from the operating engine yaws the aircraft. In order to maintain aircraft heading with the wings level, rudder must be applied toward the operating engine. This rudder force results in the sideslip condition by moving the nose of the aircraft in a direction resulting in the misalignment of the fuselage and the relative wind. This condition usually allows the pilot to maintain aircraft heading; it produces a high drag condition that significantly reduces aircraft performance. Zero Sideslip Condition The solution to maintaining aircraft heading and reducing drag to improve performance is the Zero Sideslip Condition. When the aircraft is banked into the operating engine, the bank angle creates a horizontal component of lift. The horizontal lift component aids in counteracting the turning moment of the operating engine, minimizing the rudder deflection required to align the longitudinal axis of the aircraft to the relative wind. In addition to banking into the operating engine, the appropriate amount of rudder required is indicated by the inclinometer ball being split toward the operating engine side. The Zero Sideslip Condition aligns the fuselage with the relative wind to minimize drag and must be flown for optimum aircraft performance. 01062025.draft.npc / page 8 Maintaining Zero sideslip Zero sideslip should always be maintained in a one-engine inoperative to ensure the best performance of the airplane and low Vmc speed even when turning, climbing, and descending. The rule of thumb for zero sideslip is to bank 2-3 deg into the operative engine and “brick” (slip and skid indicator) half deflection into the operative engine. The below attitude should be maintained at all times. Left engine INOP zero sideslip attitude visualized Right engine INOP zero sideslip attitude visualized 01062025.draft.npc / page 9 0° bank When 0° bank is maintained, the relative wind comes from the inoperative engine side of the airplane. This creates a fuselage lift toward the operating engine. Rudder force towards the operating engine combined with the fuselage lift helps us counteract the yaw towards the inoperative engine. Since the airplane is not banked, it creates no horizontal component of lift. The yaw towards the inoperative engine is countered purely by the rudder when 0 ° bank is maintained. This results in a moderate Vmc. The fuselage lift created by the relative wind results in more induced drag, which results in a moderate drag. 0 ° bank visualized 01062025.draft.npc / page 10 2-3° bank towards the Operating Engine (ZERO SIDESLIP) When 2-3 ° bank is maintained towards the inoperative engine, the relative wind is aligned with the longitudinal axis of the airplane, which creates no fuselage lift. To counteract the yaw towards the inoperative engine, horizontal component of lift (from banking 2-3° towards the operating engine), and rudder force are used. The horizontal component of lift helps counteract the yaw towards the inoperative engine, which helps us acquire low Vmc speed, but not as much as 8° bank into the operating engine. The lack of fuselage lift in a zero sideslip minimizes the induced drag created which gives us minimum drag. Zero sideslip visualized 01062025.draft.npc / page 11 8° bank towards the Operating Engine When 8° bank is maintained towards the inoperative engine, the relative wind comes toward the operative engine side. This creates a fuselage lift towards the inoperative engine which is added onto the yaw towards the inoperative engine. This force needs to be counteracted by the Horizontal component of lift and rudder force to maintain the aircraft’s heading. The increased horizontal component of lift towards the operating engine helps to counteract the yaw towards the inoperative engine a lot which helps to acquire the lowest Vmc speed. However, the induced drag created by fuselage lift, rudder force, and horizontal component of lift is also increased, which gives you moderate drag. 8 ° bank towards operating engine visualized 01062025.draft.npc / page 12 5° bank towards the INOPERATIVE Engine When 5° bank is maintained towards the inoperative engine, the relative wind comes from the inoperative engine side. Because the airplane is banked towards the inoperative engine, the horizontal component of lift is created towards the inoperative engine side. The combination of yaw from the inoperative engine and the horizontal component of lift (towards INOP. engine) are countered by the rudder force and the fuselage lift towards the operative engine. Since there is an addition of yaw towards the inoperative engine and the horizontal component of lift (towards INOP. engine), more rudder force is required to maintain the heading. This results in the highest Vmc. The induced drag created by the fuselage lift and rudder force creates moderate drag. 5 ° bank towards inop. engine visualized 01062025.draft.npc / page 13 Counter Rotating Engine vs Conventional Engine Counter Rotating Engines Counter rotating engines refers to a kind of engine used by a twin airplane where the left engine rotates clockwise and the right engine rotates counterclockwise. The advantages and disadvantages of using a counter-rotating engine are as below. Piper Seminole (PA-44-180) used by the MGA Flight Department is equipped with Counter Rotating Engines. Counter rotating engines refers Counter Rotating Engine visualized from the rear 01062025.draft.npc / page 14 Counter Rotating Engine thrust visualized from a bird’s eye view The single greatest advantage of counter rotating engines is that it eliminates turning tendencies. The left engine creates a left-turning tendency, and the right engine creates a right-turning tendency. Both turning tendencies counteract each other thus eliminating a Critical Engine. Disadvantages of counter rotating engines include greater expense to maintain and each engine (left and right) are mirrored and are considered two different models of engines. This makes it harder to replace the engine as the parts for the two engines are different. Conventional Engine Conventional engine refers to a kind of engine used by a twin airplane where both left and right engines rotate clockwise. The advantages and disadvantages of using a conventional engine are as below. 01062025.draft.npc / page 15 Conventional Engine visualized from the rear Conventional Engine thrust visualized from a bird’s eye view Conventional Engine lift visualized from the rear Advantages of conventional engine twin aircraft include typically a lower cost of maintenance since both engines (left and right) are identical, thus parts can be shared. 01062025.draft.npc / page 16 The greatest disadvantage of a conventional engine twin is that the turning tendencies are twice as strong. Both left and right engines create left-turning tendencies, thus the aircraft has a critical engine. 01062025.draft.npc / page 17 Determining Critical Engine Critical Engine refers to an engine if failed, would most adversely affect the performance and handling characteristics. Only conventional twin airplanes have a critical engine. Piper Seminole (PA-44-180) does not have a critical engine as it is equipped with counter-rotating engines. There are four factors that determine the critical engine (Acronym PAST) o P-Factor o Accelerated Slip Stream o Spiraling Slip Stream o Torque Effect ALL SCENARIOS BELOW ARE BASED ON CONVENTIONAL ENGINE P- Factor P- Factor refers to a phenomenon where the downward moving blade (right side of propeller) receives a higher AOA than the upward moving blade (left side of propeller). The downward- moving blade creates more thrust than the upward-moving blade. The differential thrust of the two blades creates a yawing moment to the left. Source- AOPA Pilot’s Magazine, December 2011 Lower AOA- Less thrust Higher AOA- More thrust 01062025.draft.npc / page 18 In a Conventional Twin, when the left engine is inoperative and the right engine is operative the descending blade (the blade that makes the most thrust) is farther from the Center of Gravity. A longer distance between the point of most thrust and the CG creates more yawing moments toward the inoperative engine. Ex- Arm (distance between the point of most thrust) x force (amount of thrust) = Moment (Yawing moment towards the inoperative engine) Left engine failure visualized When the right engine is inoperative and the left engine is operative the descending blade (the blade that makes the most thrust) is closer to the Center of Gravity. Less distance between the point of most thrust and the CG creates less yawing moment towards the inoperative engine. Ex- Arm (distance between the point of most thrust) x force (amount of thrust) = Moment (Yawing moment towards the inoperative engine) 01062025.draft.npc / page 19 Right engine failure visualized Accelerated Slip Stream Much like the P-Factor, the accelerated parcel of air pushed rearward by the propeller creates more lift on the part of the wing directly behind the propeller. The descending blade of the propeller creates more thrust, meaning it accelerates air rearward faster behind the descending blade (Newton’s third law), creating more lift due to faster airflow hitting the wing. When the left engine is inoperative and the right engine is operative, the wing directly behind the descending blade of the right-wing receives a faster-accelerated slipstream. Faster airflow hitting the wing creates more lift. The point of most lifts is farther away from the CG, creating more rolling moment towards the inoperative engine. 01062025.draft.npc / page 20 Left engine inoperative accelerated slip stream visualized Left engine inoperative lift visualized When the right engine is inoperative and the left engine is operative, the wing directly behind the descending blade of the left-wing receives a faster-accelerated slipstream. Faster airflow hitting the wing creates more lift. The point of most lifts is closer to the CG, creating less rolling moment towards the inoperative engine. 01062025.draft.npc / page 21 Right engine inoperative thrust visualized Right engine inoperative lift visualized Spiraling Slipstream The corkscrew movement of the rearward-pushed air behind the propeller moves rearwards and rightward. The spiraling slipstream moves towards the right due to the left side (upward moving side of the propeller) of the propeller creating less thrust, therefore creating a slower accelerated slipstream than the right side (descending side) of the propeller. Slower airflow creates higher pressure and faster airflow creates lower pressure, creating left side higher pressure airflow to move towards the right side lower pressure airflow. 01062025.draft.npc / page 22 When the left engine is failed the rearward and rightward moving spiraling slipstream created by the right engine does not reach anywhere, and has NO EFFECTS. Left engine inoperative spiraling slip stream visualized 01062025.draft.npc / page 23 When the right engine is failed the spiraling slipstream created by the left engine hits the vertical stabilizer of the airplane and creates a slight yawing moment towards the left, which helps to counteract some of the yaw towards the inoperative engine. HOWEVER, THE EFFECTS ARE SO SMALL, IT IS NEGLIGIBLE. Right engine inoperative spiraling slip stream visualized 01062025.draft.npc / page 24 Torque Effect The torque effect refers to the counter-clockwise rolling tendency of the airplane due to the propeller’s rotation towards clockwise. According to Newton’s third law, there are equal and opposite reactions to the force, thus creating a left-rolling tendency. When the left engine fails, the left rolling tendency of the torque effect created by the right engine is added on to the left yawing and rolling tendency created by the left inoperative engine. Creating a larger yawing and rolling moment towards the inoperative engine. Left engine inoperative torque effect visualized When the right engine fails, the left rolling tendency of the torque effect created by the left engine counteracts the left yawing and rolling tendency created by the right inoperative engine. Creating a weaker yawing and rolling moment towards the inoperative engine. Right engine inoperative torque effect visualized 01062025.draft.npc / page 25 Determining Critical Engine Looking at the effects of the P-Factor, Accelerated Slip Stream, Spiraling Slip Stream, and Torque Effect when a left engine failure occurs, it creates more yaw and rolls towards the inoperative engine. So we can determine that the left engine is the critical engine in a conventional twin-engine airplane. 01062025.draft.npc / page 26 Vmc Vmc refers to a speed below which aircraft control cannot be maintained if the critical engine fails (14 CFR part 23). If you maintain the aircraft at or above Vmc, it guarantees you directional control of the airplane. VMC DOES NOT GUARANTEE PERFORMANCE OF THE AIRPLANE. When a twin-engine airplane loses an engine, it experiences yaw and rolls towards the inoperative engine. Rudder towards the operative engine is required to maintain directional control of the airplane. When the airspeed of the airplane is decreased, the effectiveness of the rudder is also decreased due to less airflow around the control, however, the yaw and roll towards the inoperative engine remains the same. More rudder is required to maintain directional control. As airspeed decreases even more, there is going to be a point where the full rudder is deflected and the heading of the airplane cannot be maintained anymore, this is the point where the airplane loses directional control. Vmc of the airplane is based on the following condition • 15 CFR 25.149 - Old Regulation (not in effect anymore) o Vmc must be determined under these conditions  Most unfavorable weight (lightweight)  Most unfavorable CG (rear CG)  In the air and out-of-ground effect  Flaps takeoff position  Gear Up  Maximum takeoff power  Propeller in takeoff position  Trimmed for takeoff o Vmc must be recovered within  20 deg of heading  Without any dangerous attitudes  Requiring less than 150 lbs of force on the rudder  Without needing a decrease of power (on the operating engine) • 14 CFR 23.2135 – New Regulation (Regulation in effect) o Airplane must be Controllable under these conditions  The airplane must be controllable and maneuverable without requiring exceptional piloting skill, alertness, or strength, within the operating envelope • At all loading condition for certification is requested • During all phases of flight • With likely reversible flight control or propulsion system failure • During configuration changes 01062025.draft.npc / page 27 • Key Differences in Context: Part 23 vs. Part 25 o 14 CFR 23.2135 is aimed at smaller, often reciprocating-engine or light turbine- engine aircraft, focusing on pilot controllability in general aviation contexts. o 14 CFR 25.149 is more prescriptive and designed for transport-category aircraft, ensuring stringent safety in commercial operations. • Piper Seminole and Certification Basis o The Piper Seminole was certified under the legacy 14 CFR 23.149 standard. o Even newly manufactured Seminoles are held to this certification basis unless the manufacturer opts for recertification under the modern Part 23 framework, which is uncommon. o Pilots and operators must reference the aircraft's certification basis in the AFM/POH for accurate VMC determination and comply with the associated limitations. Recognizing and Recovering from Vmc • You can recognize you are below Vmc under any of these conditions, RECOVER IMMEDIATELY o Loss of directional control (full rudder deflected and heading is lost towards inoperative engine) o Stall warning horn o Stall buffet o Rapid decay of control effectiveness (flight control suddenly requires significantly more input to maintain positive control) • Recovery Procedure o Decrease asymmetrical thrust by reducing the operative engine’s power o Pitch down to regain the airspeed of the airplane above Vyse o Increase power on the operative engine as required to maintain positive flight controls Vmc vs Stall Speed 01062025.draft.npc / page 28 Source- Jeppesen Multi-Engine Manual As density altitude increases, the thrust produced by the propeller decreases and the engine power decreases due to decreased O2. In a situation where an engine has failed, the increased density altitude decreases Vmc because less asymmetrical thrust is created by the operative engine which results in less rudder required to maintain directional control. Vmc decreases with increasing altitude. However, the Indicated Stall Speed remains the same regardless of the altitude. At a certain altitude, the Vmc is going to be less than the Vs. If you go below Vmc above that specific altitude, recovery may be difficult as the airplane stalls and loses directional control. Higher density altitude visualized 01062025.draft.npc / page 29 Lower-density altitude visualized 01062025.draft.npc / page 30 Factors affecting Vmc A general rule of factors affecting Vmc is if more rudder is required to maintain directional control, the Vmc increases. If less rudder is required to maintain directional control, the Vmc decreases. BELOW CONDITIONS ARE BASED ON ONE ENGINE INOPERATIVE Effect On Vmc Performance Power Increase UP More asymmetrical thrust, more yaw towards inop. engine. More rudder is required. UP More power and thrust Temperature Increase, Density Altitude Increase, Pressure Decrease DOWN Less asymmetrical thrust, and less yaw towards inop. engine. Less rudder is required. DOWN Less power and thrust Feathered Propeller (Least amount of drag) (Coarse/highest pitch) DOWN Less asymmetrical drag, and less yaw towards inop. engine. Less rudder is required. UP Less parasitic drag (compared to windmilling) Windmilling Propeller UP More asymmetrical drag, and more yaw towards inop. engine. More rudder is required. DOWN More parasitic drag Flaps Down DOWN More induced drag is created behind the operating engine due to accelerated slip stream behind the propeller. Less yaw towards inop. engine. Less rudder is required. DOWN More induced drag due to flap. AFT CG UP There is less arm between the CG and the rudder. The rudder is less effective, requiring more rudder. UP Less induced drag is created as less downward lift is produced by the stabilator/horizontal stabilizer. Gear Down DOWN Nose gear extends downward and forward, moving CG to forward- Vmc DOWN Gear down creates a keel effect, increasing the stability of the airplane- Vmc DOWN DOWN More parasitic drag 01062025.draft.npc / page 31 Gear Up UP Nose gear retracts upward and rearward, moving CG to AFT- Vmc UP Keel effect is no longer produced by the gear – Vmc UP UP Less parasitic drag Heavier Weight DOWN More lift is required to maintain level flight in heavy airplanes. When the airplane is banked towards the operative engine, there is more horizontal component of lift produced. The HCL counteracts some of yaw to the inop. engine. Less rudder is required DOWN More lift is required, more induced drag is created Critical Engine Failure (When compared to non- critical engine failure) UP P.A.S.T (Factors determining critical engine) creates more yaw to the inop. engine when critical engine is failed. More rudder is required DOWN More rudder is required to maintain zero sideslip. More rudder deflection creates more induced drag on the horizontal stabilizer In Ground Effect UP Less induced drag causes reduction in thrust required (meaning an airplane has extra thrust). Creates more yaw to the inop. engine. More rudder is required. UP Less induced drag is created due to ground preventing wingtip vortices traveling to the top of the wing. Which prevents lift vectoring backwards. Cowl Flap Open DOWN More induced drag is created behind the operating engine due to the accelerated slip stream behind the propeller. Less yaw towards inop. engine. Less rudder is required DOWN More induced drag due to flap. 01062025.draft.npc / page 32 Speeds, Weight, and PerformanceSeminole PA-44-180 Speeds Vso (stall speed landing config.) 55 KIAS (bottom white arc) Vmc (min. control speed) 56 KIAS (red radial line) Vs (stall speed zero flaps) 57 KIAS (bottom green arc) Vr (short TO) 70 KIAS Vx 82 KIAS Vy 88 KIAS Vxse (single-engine best angle of climb) 82 KIAS Vyse (single-engine best rate of climb) 88 KIAS (blue radial line) Vsse (min. intentional OEI speed) (SIMULATED ENGINE FAILURE MAY NOT BE ATTEMPTED BELOW THIS SPEED) 82 KIAS Enroute climb 105 KIAS Vno (max. structural cruising speed) 169 KIAS (top green arc) Vne (never exceed speed) 202 KIAS (top red radial) Va (design maneuvering speed) 2700 lb 112 KIAS 3800 lb 133 KIAS Vfe (max flap ext. speed) 111 KIAS Vle (max landing gear extended speed) 140 KIAS Vlo Down (max landing gear extension) 140 KIAS Vlo Up (max landing gear retraction) 109 KIAS Max door open speed 82 KIAS Approach for Normal Landing Aprox. 80 KIAS (when runway is made) Approach for Short Field Landing Aprox. 75 KIAS (when runway is made) 01062025.draft.npc / page 33 Seminole PA-44-180 Weights Max Ramp Weight 3816 lbs Max Takeoff Weight 3800 lbs Max Landing Weight 3800 lbs Max Baggage Weight 200 lbs 01062025.draft.npc / page 34 Takeoff and Landing Accelerate Stop Distance Accelerate stop distance must be calculated before taking off. Accelerate stop distance guarantees that the airplane will accelerate to Vr or Vlof or manufacture specified speed and experience an engine failure, and bring the airplane to a complete stop. Accelerate go distance is the distance required to continue the takeoff and climb to 50 feet assuming that an engine failure has occurred at Vr or Vlof or manufacture specified speed. MGA DOES NOT PERMIT SINGLE-ENGINE TAKEOFF. Source- Airplane Flying Handbook Chapter 13 To calculate the accelerate stop distance, refer to the example below. Sample Question- Temp 20 deg, Pressure Altitude 2500’, 3500 lb TO weight, 10 KIAS headwind Answer- approximately 2650’ 01062025.draft.npc / page 35 Normal Takeoff Distance Sample Question- Temp 20 deg, Pressure Altitude 2500’, 3500 lb TO weight, 10 KIAS headwind Answer- approximately 1300’ 01062025.draft.npc / page 36 Short Field Landing Distance Sample Question- Temp 20 deg, Pressure Altitude 2500’, 3500 lb TO weight, 10 KIAS headwind Answer- Approximately 490’ 01062025.draft.npc / page 37 Time Fuel and Distance to Climb Sample Question- Departure airport temp 20 deg, Cruise altitude temp 15 deg, Climb from 2000’ Press. Alt. to 5000’ Press. Alt., Cowl flap Open, Flaps Up, Full throttle at 2700 RPM. Step 1- Find time, fuel, and distance to climb at the departure airport using the departure airport temp and press. alt. Time – 2 min, Fuel – 1 gal., Distance – 3 nm Step 2- Find time, fuel, and distance to climb at cruising altitude using the cruising altitude temp and press. alt. Time – 5 min, Fuel – 3 gal, Distance – 8 nm Answer- Time 5 – 2 = 3 min. Fuel 3 – 1 = 2 gal (add 2.6 gal if you are adding start, taxi, and runup fuel) Distance 8 – 3= 5 nm (not accounted for any winds) 01062025.draft.npc / page 38 Cruise Performance Fuel and Power Setting Table PER ENGINE Sample Question- 5000’ Press. Alt., 15 deg, 75% power, 2400 RPM, 23 MP Answer- Fuel flow 23.4 GPH (11.7 x 2 accounted for two engines), Recommended 24.8 MP (accounted from the NOTE and nonstandard temp) Speed Power Conditions- 5000’ Press. Alt., 15 deg, 75% power, Cowl Flap Closed, Gear and Flaps UP Answer- 162 KIAS at 75% power, 23.3 GPH. 01062025.draft.npc / page 39 Ceiling Source- Pilot’s Handbook of Aeronautical Knowledge Chapter 11 • Absolute Ceiling o Altitude where the airplane produces zero Rate of Climb (the point where Vy meets Vx) • Service Ceiling o Altitude where the airplane produces 100 feet per minute climb • Single-engine Absolute Ceiling o Altitude where a multi-engine airplane with one engine operative produces zero Rate of Climb • Single-engine Service Ceiling o Altitude where a multi-engine airplane with one engine operative produces 50 feet per minute climb When an airplane is flying at an absolute ceiling and experiences an engine failure, the airplane will drift down to the single-engine absolute ceiling even when it maintains Vyse. 01062025.draft.npc / page 40 Calculating Absolute Ceiling Step 1- Use the climb performance chart based on the configuration of the airplane Step 2- Draw a straight line up from 0 FPM to the aircraft’s weight Step 3- Draw a straight line horizontally across from the intersection point to the left Step 4- Find how much the winds aloft is above STD temperature Step 5- Draw a line parallel to the STD TEMP reference line. Step 6- The intersection point is the Absolute Ceiling Sample Question- 3800 lbs, the temperature at 12,000 is 15 deg above STD temp Answer- Approximately 12500’ (rounded down for safety)