Commercial Certification (FAA)
25.107
Takeoff Speeds
flying qualities
AEO Takeoff, Abused - Early Rotation, Rapid Rotation, Excessive Rotation, Mistrim
See AC 25-7A Section 2 Para 10 b 1. Rotate @ Vr - 7% or 10 Kts, whichever is less, below Vr. Not more than 1% increase in takeoff distance. 2. Rotate @ Vr, but mistrim +/- 2 units of pitch trim w/o config warning. Not more than 1% increase in T/O dist. 3. Use rapid rotation rate or rotate 2 deg above normal pitch attitude (two different tests). Tail strikes acceptable if "minor" & not unsafe!
Aircraft departs runway / Inadvertent ground contact.
Civil Transport (Part 25)
Turbojet, Turbofan
Both Inhabited and Uninhabited Aircraft
Medium
FAA Order 4040.26
Depart Runway: 1. Cut engines 2. Cut fuel to engines 3. Cut all remaining electrical power
Stall: 1. Apply maximum available power 2. reduce angle of attack below stall 3. Allow vehicle to accelerate and climb 4. If you contact ground, consider accomplishing steps for departing runway.
1. Inability to rotate. 2. Over rotation / stall on takeoff.
1. All testing to be conducted on hard surfaced, dry runway under day VFR conditions.
2. Minimum runway length and width must be established.
3. Crash and rescue crews to be briefed on conduct of tests, aircraft familiarization, and rescue procedures. Equipment and crews to be positioned a minimum of 400 feet from the runway centerline.
4. Minimum essential flight crew on board.
5. Flight crew will wear protective clothing and helmets.
6. Wind speed must be 5 knots or less from any direction except no tail wind is permitted.
7. Inspect tires, struts and brakes prior to test. Service to recommended limits.
8. One flap configuration should be completed prior to going on to the next flap configuration.
9. Engineering analysis to determine preparation for this test by analysis of development data during AEO / OEI takeoff speed schedule testing.
10. Engineering to ensure tail bumper is structurally adequate for tail strike (over-rotation)
11. Instrumentation to include cockpit display of tail proximity indicator, pitch attitude; tail bumper contact to be recorded on instrumentation data.
12. Telemetry to be utilized for each run, and will provide feedback to the flight crews.
13. Ensure display and required parameters are active for each flight.
14. Crew preparation to include review of previous data and procedures to be followed in the event of a tail strike or stall warning at liftoff.
15. Aircraft preparation to include regular inspection of the tail bumper, tail proximity probe, and tail structure if the tail strikes.
16. Perform buildup test point at Vr-5.
17. Two Engine Takeoff Performance at normal scheduled speeds (Vr, V2+10) must be satisfactorily completed prior to these tests.
Reduces Probability
Analysis
Stall/loss of lift out of ground effect (OGE)
Perform analysis of In-ground effect (IGE) influence on stall speeds and stall angle-of-attack (AOA)
Reduces Probability
Analysis
Test aircrew should be aware that during on-ground/low altitude testing, such as field performance or VMU determination, certain aircraft designs may be more susceptible to IGE. IGE typically increases stall speed and reduces stall AOA compared to free air values. In addition, since IGE at a point on the wing is a function of its height above the runway, rotation of swept wings increases IGE influence due to a reduction of wing height above runway. This may result in span-wise variations of IGE and related impact to AOA. A thorough knowledge of free air stall speeds and characteristics is also important as a prerequisite to assess the risk of potential stall during on-ground/low altitude testing.
The analysis includes reduction in CLmax with proximity to the ground as a function of height divided by wing span. This analysis should include consideration of the allowable bank angles as well as the effects of wing sweep in proximity to the ground during rotation and landing. The impact of this reduction in CLmax would be reduced stall AOA values and increased stall speeds when near the ground as compared to free air results.
Assess stall warning prevention system design for OGE effects
Reduces Probability
Analysis
Stall warning and prevention devices should be thoroughly understood by the test crews, particularly as to whether these protection features have any limitations. Test crews should understand the transitional scheduling (i.e. as a function of altitude, speed, acceleration, and rates) of stall warning cues used during maneuvers.
Changes to the estimates of stall AOA as well as the stall warning and prevention device settings should be thoroughly reviewed and understood by the test team prior to use.
Perform pilot-in-the-loop simulations of maneuvers. Though simulations with OGE model enhancements are preferred, models without OGE effects can help provide pilot the ability to assess impending conditions for an OGE stall recognition and recovery.
Reduces Probability
Training
The aerodynamic stall recognition, characteristics, and recovery techniques should be understood by the test crew performing the takeoff and landing tests.
Limit test crew cadre to maximize experience carryover, improved recovery technique and impending stall recognition
Reduces Probability
Design
Monitor AoA conditions and establish standard limits calls for impending OGE stall conditions.
Reduces Probability
Procedure
Flight Crew wears helmets and fire proof clothing
Reduces Severity
Safety Features
