519 

Federal Aviation Administration, DOT 

Pt. 135, App. A 

(2) At speeds between 

V

mo

and 

V

c,

the loads 

resulting from the disconnection of the en-
gine compressor from the turbine or from 
loss of the turbine blades are considered to 
be ultimate loads. 

(3) The time history of the thrust decay 

and drag buildup occurring as a result of the 
prescribed engine failures must be substan-
tiated by test or other data applicable to the 
particular engine-propeller combination. 

(4) The timing and magnitude of the prob-

able pilot corrective action must be conserv- 
atively estimated, considering the character-
istics of the particular engine-propeller-air-
plane combination. 

(b) Pilot corrective action may be assumed 

to be initiated at the time maximum yawing 
velocity is reached, but not earlier than 2 
seconds after the engine failure. The mag-
nitude of the corrective action may be based 
on the control forces in FAR 23.397 except 
that lower forces may be assumed where it is 
shown by analysis or test that these forces 
can control the yaw and roll resulting from 
the prescribed engine failure conditions. 

Ground Loads 

27. 

Dual wheel landing gear units. 

Each dual 

wheel landing gear unit and its supporting 
structure must be shown to comply with the 
following: 

(a) 

Pivoting. 

The airplane must be assumed 

to pivot about one side of the main gear with 
the brakes on that side locked. The limit 
vertical load factor must be 1.0 and the coef-
ficient of friction 0.8. This condition need 
apply only to the main gear and its sup-
porting structure. 

(b) 

Unequal tire inflation. 

A 60–40 percent 

distribution of the loads established under 
FAR 23.471 through FAR 23.483 must be ap-
plied to the dual wheels. 

(c) 

Flat tire. 

(1) Sixty percent of the loads 

in FAR 23.471 through FAR 23.483 must be ap-
plied to either wheel in a unit. 

(2) Sixty percent of the limit drag and side 

loads and 100 percent of the limit vertical 
load established under FARs 23.493 and 23.485 
must be applied to either wheel in a unit ex-
cept that the vertical load need not exceed 
the maximum vertical load in paragraph 
(c)(1) of this section. 

Fatigue Evaluation 

28. 

Fatigue evaluation of wing and associated 

structure. 

Unless it is shown that the struc-

ture, operating stress levels, materials and 
expected use are comparable from a fatigue 
standpoint to a similar design which has had 
substantial satisfactory service experience, 
the strength, detail design, and the fabrica-
tion of those parts of the wing, wing carry-
through, and attaching structure whose fail-
ure would be catastrophic must be evaluated 
under either— 

(a) A fatigue strength investigation in 

which the structure is shown by analysis, 
tests, or both to be able to withstand the re-
peated loads of variable magnitude expected 
in service; or 

(b) A fail-safe strength investigation in 

which it is shown by analysis, tests, or both 
that catastrophic failure of the structure is 
not probable after fatigue, or obvious partial 
failure, of a principal structural element, 
and that the remaining structure is able to 
withstand a static ultimate load factor of 75 
percent of the critical limit load factor at 

V

C.

 

These loads must be multiplied by a factor of 
1.15 unless the dynamic effects of failure 
under static load are otherwise considered. 

Design and Construction 

29. 

Flutter. 

For multiengine turbopropeller 

powered airplanes, a dynamic evaluation 
must be made and must include— 

(a) The significant elastic, inertia, and aer-

odynamic forces associated with the rota-
tions and displacements of the plane of the 
propeller; and 

(b) Engine-propeller-nacelle stiffness and 

damping variations appropriate to the par-
ticular configuration. 

Landing Gear 

30. 

Flap operated landing gear warning de-

vice. 

Airplanes having retractable landing 

gear and wing flaps must be equipped with a 
warning device that functions continuously 
when the wing flaps are extended to a flap 
position that activates the warning device to 
give adequate warning before landing, using 
normal landing procedures, if the landing 
gear is not fully extended and locked. There 
may not be a manual shut off for this warn-
ing device. The flap position sensing unit 
may be installed at any suitable location. 
The system for this device may use any part 
of the system (including the aural warning 
device) provided for other landing gear warn-
ing devices. 

Personnel and Cargo Accommodations 

31. 

Cargo and baggage compartments. 

Cargo 

and baggage compartments must be designed 
to meet FAR 23.787 (a) and (b), and in addi-
tion means must be provided to protect pas-
sengers from injury by the contents of any 
cargo or baggage compartment when the ul-
timate forward inertia force is 9

g. 

32. 

Doors and exits. 

The airplane must meet 

FAR 23.783 and FAR 23.807 (a)(3), (b), and (c), 
and in addition: 

(a) There must be a means to lock and 

safeguard each external door and exit 
against opening in flight either inadvert-
ently by persons, or as a result of mechan-
ical failure. Each external door must be op-
erable from both the inside and the outside. 

(b) There must be means for direct visual 

inspection of the locking mechanism by 

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