Inertial Navigation and Surveying System Installation

INTRODUCTION

Static-strength substantiation of the DHC-8-100 Inertial Navigation and Surveying System (INSGPS) installation. The assessment follows the physical load path from the equipment through the tray, support angles, angle/channel beams and Tee Clips into the existing aircraft structure.

Classical 3D rigid-body equilibrium and beam methods are used to resolve attachment loads, establish joint capacity, and check member strength and local stability against the source material allowables.

AircraftDHC-8-100Exterior structural installation

Installation envelopeX370.8 → X387.35Between stringers 32P and 32S

Conservative payload25.11 lb₍f₎Added structure + equipment, including 15% installation allowance

Substantiation routeClassical + 3D rigid-bodyFasteners, tray, support angles, angle beam and tee clip

Technical figure from the Inertial Navigation and Surveying System structural substantiation. — Inertial Navigation and Surveying System installation on the DHC-8-100.

DESIGN ASSESSMENT

LONGITUDINAL LOCATIONX370.8 → X387.35

The installation occupies a compact center-fuselage envelope around the X380 analysis station.

LATERAL BOUNDARYStringers 32P ↔ 32S

Load is introduced into the adjacent keel/floor support structure and stringer attachments.

PRIMARY LOAD PATHEquipment → Tray → Support Angles

Tray reactions feed the FWD/AFT supports before entering the angle/channel beam structure.

AIRCRAFT TIE-INAngle Beam + Tee Clip

The final load path is transferred into existing floor/keel structure and the adjacent stringer system.

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Load-path driven substantiation

The analysis is organized by successive load-transfer interfaces rather than by part description: equipment bolts → tray bolts → support-angle joints → beam joints → aircraft tie-ins.

Load-Path Rationale

I traced the installation as a sequence of discrete interfaces rather than treating it as one equivalent bracket. Equipment inertia is introduced into the tray through the four AN3-7 mounting bolts; the tray transfers the combined payload to the FWD and AFT support angles through AN4-6 bolts. Those reactions then enter the Angle Beam / Channel Beam through Hi-Lok pin-collar joints and finally close into the existing floor-keel and stringer structure through the beam and Tee-Clip attachments. Keeping each interface explicit makes the reaction path auditable and allows the governing fastener, bearing, bending, and local clip checks to be assessed at the physical load-transfer location.

INSGPS Installation Components

PRIMARY PAYLOAD SUPPORT0.071 in AL 2024-T3 ALCAD tray

The tray receives the equipment inertia through four AN3-7 mounting bolts and transfers the combined load into the support angles through AN4-6 bolts.

SUPPORT MEMBERSAL 6061-T6511 extrusions

FWD/AFT support angles, flange angles, Tee Clips, Angle Beam and Channel Beam provide the principal metallic load-transfer path.

AIRCRAFT TIE-IN7075-series existing structure

Loads close into the keel/floor support structure and stringers 32P/32S through the beam and Tee-Clip attachments.

JOINT TYPESAN3 / AN4 + Hi-Lok pin-collar

Joint checks include fastener shear/tension, local bearing, and conservative single-plane credit where required by the source assessment.

INSGPS Installation Weight Estimation

WEIGHT BUILD-UP

CAD volume × material density

AL 2024-T3 sheet uses 0.100 lbₘ/in³ and AL 6061-T6511 extrusion uses 0.098 lbₘ/in³. Equipment weight is included directly from the source data.

INSTALLATION ALLOWANCE

15% weight growth

Each added component is scaled by 1.15 to account for installation hardware, fasteners and wiring/cabling that are not modeled individually.

REFERENCE AXES

(X,Y,Z) = (AFT, Right, Up)

CoG coordinates are measured from the lower-right corner of the FWD Angle Beam.

Conservative installation mass model retained for structural analysis.

Quantity	Source value	Engineering use
Base added system weight	21.84 lb	CAD/material build-up plus equipment
Installation allowance	15%	Fasteners, wiring/cabling and unmodeled installation items
Conservative analysis payload	25.11 lb_f	Applied to the tray and downstream interfaces
Weighted CoG	(8.08, −9.12, 1.77) in	Measured from the FWD Angle Beam reference corner

Weighted-Average CoG

\bar{x}=\frac{\sum_i W_i x_i}{\sum_i W_i}

\bar{y}=\frac{\sum_i W_i y_i}{\sum_i W_i}

\bar{z}=\frac{\sum_i W_i z_i}{\sum_i W_i}

A worked check for the X-coordinate is:

\bar{x}=\frac{1.16(7.75)+0.02(-0.20)+0.03(10.25)+0.20(10.01)+0.20(0.34)+0.20(0.34)+0.20(10.11)+0.20(10.11)+1.31(-0.15)+0.75(10.37)+1.01(0.50)+2.35(9.54)+17.49(8.98)}{25.11}\approx\boxed{8.08\,in}

The same procedure produces $\bar{y} = - 9.12 in$ and $\bar{z} = 1.77 in$ .

Conservative analysis payload · 25.11 lb₍f₎

Weighted CoG = (8.08, −9.12, 1.77) in from the FWD Angle Beam reference corner. The complete added-system weight is conservatively treated as payload carried by the tray.

Material Properties

The portfolio summary retains the material values that govern the principal member and joint checks. The full source report contains the complete thickness-dependent MMPDS/MMEAVS table.

Selected structural material allowables used in the retained checks.

Material / form	F_tu	F_cy	F_su	Typical use
AL 2024-T3 CLAD sheet, 0.063–0.128 in	62 ksi	37 ksi	38 ksi	Tray
AL 6061-T6/T6511 extrusion	38 ksi	34 ksi	26 ksi	Support angles / beams / clips
AL 7075-T6511 extrusion	78 ksi	70 ksi	41 ksi	Stringer structure
AL 7075-T6/T62 sheet, 0.012–0.039 in	74 ksi	67 ksi	47 ksi	Existing sheet structure
AL 7075-T73 sheet, 0.040–0.249 in	67 ksi	55 ksi	38 ksi	Existing keel-angle structure

Fasteners Allowables

Joint allowable philosophy

Size the connection to the weakest applicable failure path for the actual fastener / sheet stack rather than the isolated fastener strength.

P_{allow} = \min (P_{fastener shear}, P_{joint static}, P_{bearing})

Sheet thickness and material can govern the joint.Countersunk geometry is treated with the applicable static-joint reduction.Fastener tension is checked where a meaningful tensile reaction exists.

The usable joint allowable is based on the weakest applicable failure path for the actual fastener/sheet stack rather than on isolated fastener strength.

HL18PB / HL70 · Support-angle joints

Joint stack0.25 in AL 6061-T6511 support angle + 0.1875 in angle/channel beam Pin shear2,005 lb_f Thin-layer bearing2,402 lb_f Governing shear allowable2,005 lb_f Pin tensile1,940 lb_f Collar tensile / governing tension1,400 lb_f

HL18PB / HL70 · Tee Clip to Stringer

Conservative stack0.125 in AL 6061-T6511 Tee Clip + 0.080 in AL 7075-T6511 stringer Physical jointFour shear planes are present Credited shear planesOne only - conservative Pin shear2,005 lb_f Stringer bearing1,750 lb_f Governing shear / tension1,750 / 1,400 lb_f

AN4-6A · Tray to Support Angles

Joint stack0.071 in AL 2024-T3 tray + 0.25 in AL 6061-T6511 support Bolt single shear3,680 lb_f Tray bearing2,218 lb_f Governing shear allowable2,218 lb_f Tensile allowable4,080 lb_f Failure pathTray bearing governs shear-side sizing

AN3-7A · INSGPS Equipment to Tray

Joint stackEquipment flange + 0.071 in AL 2024-T3 tray Bolt single shear2,125 lb_f Tray bearing1,686 lb_f Governing shear allowable1,686 lb_f Tensile allowable2,210 lb_f Failure pathTray bearing governs shear-side sizing

LOAD CASES FORMULATION

REGULATORY SOURCE BASISFAR criteria used to establish the applicable structural load environment

Flight loads · FAR 25.321 and 25.331–25.351

General flight-load requirements
Maneuver and flight-envelope conditions
Design airspeeds and maneuver load factors
Gust/turbulence, high-lift, rolling and yaw conditions

Source-derived regulatory criteria; visually separated from installation-specific engineering analysis.

Emergency landing context · FAR 25.561

Forward: 9 g
Downward: 6 g
Upward: 3 g
Sideward: 3 g on airframe; 4 g on seats/attachments
Rearward: 1.5 g

The installation spans X370.8–X387.35. The source analysis uses X380.00 as a conservative station and retains the governing flight acceleration in each direction. A 1.5 factor is carried explicitly from limit to ultimate demand.

LIMIT → ULTIMATE

Ultimate factor retained explicitly

The source uses a 1.5 factor between limit and ultimate demand.

N_{u} = 1.5 N_{limit}

Governing limit-load cases used for structural substantiation.

Load Case Number	Load Factor Direction	The Governing Limit Load Case (g)	Governing basis
Load Case Number	Load Factor Direction	The Governing Limit Load Case (g)	Governing basis
1	Upward	3.72	Flight
2	Downward	5.1	Flight
3	Outboard	0.96	Flight
4	Inboard	0.97	Flight
5	Forward	0.57	Flight
Not required*	Aft	0.11	Covered conservatively by Forward case
*This case is covered by the Forward case, so it will not be required

Load-Case Selection Rationale

The installation is treated as an exterior aircraft modification, so the substantiation is driven by the governing flight accelerations rather than cabin emergency-landing factors. I selected the conservative X380 station within the installation envelope and retained the worst limit acceleration in each direction: 3.72g Upward, 5.10g Downward, 0.96g Outboard, 0.97g Inboard, and 0.57g Forward. The 0.11g Aft case is enveloped by the Forward case and is therefore not modeled separately. This keeps the load set complete, traceable, and free of a redundant weaker reverse-direction case.

CLASSICAL ANALYSIS

1Equipment mounting

Resolve four AN3-7 bolt reactions with 3D rigid-body equilibrium.

2Tray

Resolve AN4-6 reactions and idealize tray response in principal L/LT directions.

3Support angles

Use simply supported beam models with conservative peak bolt loads.

4Aircraft tie-in

Carry demand through the Angle Beam and Tee Clip into the existing structure.

25.11

Common conservative payload basis

The complete 25.11 lb₍f₎ added-system weight is treated as tray payload at the weighted CoG so each downstream interface is checked against an intentionally conservative common load basis.

Governing retained structural results.

Assessment	Governing demand / method	Result	Status
Tray Beam A · tension	36.53 ksi limit stress; 1.5 ultimate factor	MS = +0.13	PASS
Tray Beam A · compression/bending interaction	Cozzone / modulus-of-rupture treatment	MS = +0.547	PASS
FWD Support Angle	0.94 ksi tension / −0.73 ksi compression	Below 6061-T6511 allowables	PASS
Angle Beam · combined stress	19.92 ksi tension / −13.87 ksi compression	MS = +0.27 / +0.63	PASS
Angle Beam · flange crippling	15.36 ksi applied vs 31.06 ksi crippling	MS = +0.35	PASS
Tee Clip	Top: 280.09 psi shear / 945.11 psi normal	Below 6061-T6511 allowables	PASS

GOV

Minimum retained margin: +0.13

The tray longitudinal Beam A tensile check is the tightest explicit margin retained in this portfolio summary. All retained member and joint checks remain positive or pass by the source observation criteria.

MOUNTING

4 × AN3-7 bolts

Equipment CoG = (8.98, −9.12, 2.65) in. The full 25.11 lb₍f₎ conservative payload is used for attachment screening.

LOAD EXTRACTION

3D rigid-body equilibrium

For each flight direction, the solver resolves bolt-group shear, compression/tension and the moment about the fastener-group centroid.

Maximum shear and axial demand at one INSGPS equipment mounting bolt .

	Shear (lb_f)	Axial
	Shear (lb_f)	Compression (lb_f)	Tensile (lb_f)
0.57g Forward Case	3.58	1.66	1.66
0.97g Inboard Case	6.21	4.60	4.60
0.96g Outboard Case	6.15	4.55	4.55
3.72g Upward Case	0.00	0.00	24.03
5.1g Downward Case	0.00	32.94	0.00
MAXIMUM	6.21	32.94	24.03

Engineering readout. The governing per-bolt demand is 6.21 lb_f shear, 32.94 lb_f compression and 24.03 lb_f tension. The AN3-7A joint allowable retained from the source is 1,686 lb_f in shear and 2,210 lb_f in tension, so the equipment attachment is non-governing. The resolved bolt-group moments are carried forward into the tray assessment.

Resultant moment about the INSGPS equipment fastener-group centroid for each load case.

	M_x (in-lb_f)	M_y (in-lb_f)	M_z (in-lb_f)
0.57g Forward Case	0.00	-31.13	0.07
0.97g Inboard Case	52.98	0.00	-3.73
0.96g Outboard Case	-52.43	0.00	3.69
3.72g Upward Case	0.47	-14.31	0.00
5.1g Downward Case	-0.64	19.63	0.00

INSGPS Tray

Four AN4-6 bolts transfer the conservative 25.11 lb_f payload into the FWD and AFT supports. The governing resolved tray-bolt values are 8.06 lb_f shear and 47.78 lb_f axial demand in the source reaction table.

Tray-attachment bolt resultant shear and axial demand.

	Bolt #1		Bolt #2		Bolt #3		Bolt #4
	Shear Load	Axial Load	Shear Load	Axial Load	Shear Load	Axial Load	Shear Load	Axial Load
	(lb_f)		(lb_f)		(lb_f)		(lb_f)
0.57g FORWARD CASE	3.58	1.30	3.58	1.30	3.58	-1.30	3.58	-1.30
0.97g INBOARD CASE	4.49	2.79	4.49	-2.79	8.06	2.79	8.06	-2.79
0.96g OUTBOARD CASE	4.44	-2.76	4.44	2.76	7.98	-2.76	7.98	2.76
3.72g UPWARD CASE		-11.85		-11.92		-34.79		-34.85
5.1g DOWNWARD CASE		16.25		16.34		47.69		47.78
MAX SHEAR	8.06
MAX TENSILE	47.78
MAX COMPRESSIVE	-34.85

Tray Idealization Rationale

I decomposed the tray into two orthogonal beam strips because the source reactions and moments naturally separate into the tray’s longitudinal (L) and transverse (LT) directions. Beam A receives the longitudinal force system and bending about the transverse axis; Beam B receives the lateral force system and the complementary bending component. Loads omitted from one strip are explicitly carried by the other, while torsional components are conservatively assigned to the adjacent structural load path. This keeps the hand calculation transparent without double-counting reaction components.

BEAM A · L DIRECTION

Longitudinal tray response

Fastener reactions at the FWD and AFT ends are grouped to capture axial force and bending in the tray’s principal longitudinal direction.

BEAM B · LT DIRECTION

Transverse tray response

Port and starboard fastener reactions are grouped to capture transverse axial/bending response independently.

DECOUPLING

Assign each reaction to the governing plane

Longitudinal reactions are carried by Beam A and lateral reactions by Beam B; corresponding x/y bending moments are assigned to the beam that represents that plane.

TORSIONAL SIMPLIFICATION

Adjacent structure carries secondary torsion

The source idealization neglects the non-governing torsional component in the orthogonal beam model to keep the hand analysis tractable while preserving the primary bending/axial load paths.

Condensed governing tray-beam response used for the hand checks.

Idealized member	Peak axial	Peak shear	Governing bending moments
Beam A · longitudinal	7.16 lb_f	65.80 lb_f	M_y = +188.082 / −257.9 in-lb_f; M_z = ±3.73 in-lb_f
Beam B · transverse	12.18 lb_f	64.11 lb_f	M_x = ±26.52 in-lb_f; M_z = ±3.73 in-lb_f

Beam A is governing. Elastic bending gives a maximum 36.53 ksi tensile stress. Because the source notes that this enters the plastic range, the retained assessment uses the Cozzone plastic-bending method and the cross-section shape factor to establish a bending modulus of rupture.

${F_{b,y} = F_{\max} + F_{o}\left( k_{y} - 1 \right) }{= 62 + 54.79(1.4163 - 1) }{= \boxed{84.81\ ksi}}$

{M.S}_{t} = \frac{62}{36.53 \times 1.5} - 1 = 0.13

\boxed{{M.S}_{t} = 0.13\ }

→ PASS

{M.S}_{c} = \frac{1}{1.5\left( R_{A,max} + R_{b,max} \right)} - 1 = \frac{1}{1.5(0.000274054 + 0.431)} - 1

\boxed{{M.S}_{c} = 0.547\ }

→ PASS

Beam B produces much smaller axial and bending stresses and passes by observation in the source analysis.

FWD Support Angle

LOAD SOURCEPeak AN4-6 tray-bolt reactions

IDEALIZATIONL-section simply supported beam · two point loads

DOWNSTREAM JOINT14 × HL18PB/HL70 pin-collar fasteners

The support is conservatively loaded with peak tray-bolt components combined as if simultaneous, intentionally overbounding the member and its downstream Hi-Lok joint.

FWD Support Angle governing reactions, axial load and bending moments.

Direction		+	-	Unit
R_x Reaction Force	End A	4.29	2.15	lb_f
R_x Reaction Force	End B	2.87	0.75	lb_f
R_y Reaction Force	End A	7.85	7.93	lb_f
R_y Reaction Force	End B	7.85	7.93	lb_f
R_z Reaction Force	End A	34.04	46.96	lb_f
R_z Reaction Force	End B	35.66	48.60	lb_f
Beam Axial Force	-	7.93x2=15.86	7.85x2=15.7	lb_f
M_x Bending Moment	-	81.45	110.57	lb_f-in
M_z Bending Moment	-	10.72	5.9	lb_f-in

The retained beam check gives maximum combined stresses of 0.94 ksi tension and −0.73 ksi compression, well below the AL 6061-T6511 strength basis.

The same source model also checks local tension-clip action by converting the flange eccentricity into additional fastener tension:

{f_{t,\ AN46} = 2 \times 35.66 + \frac{3}{4}\ \frac{69.7\ \times 1}{0.625} }{= 154.96{\ lb}_{f}}

{f_{t,\ YA5} = 7.16 + \frac{3}{4}\ \frac{7.16 \times 1.6}{1.9375 - 1.6} }{= 32.62{\ lb}_{f}}

The source compares 154.96 lb_f at the AN4-6 side and 32.62 lb_f at the HL18PB/HL70 side against 4,080 lb_f and 1,400 lb_f tensile allowables, respectively; both pass.

AFT Support Angle

LOAD SOURCEPeak AN4-6 tray-bolt reactions

IDEALIZATIONL-section simply supported beam · two point loads

DOWNSTREAM JOINT14 × HL18PB/HL70 pin-collar fasteners

The AFT member uses the same conservative peak tray-bolt envelope, with geometry-specific eccentricity and reactions.

AFT Support Angle governing reactions, axial load and bending moments.

Direction		+	-	Unit
R_x Reaction Force	End A	3.77	1.64	lb_f
R_x Reaction Force	End B	3.39	1.26	lb_f
R_y Reaction Force	End A	7.85	7.93	lb_f
R_y Reaction Force	End B	7.85	7.93	lb_f
R_z Reaction Force	End A	36.18	49.13	lb_f
R_z Reaction Force	End B	33.52	46.43	lb_f
Beam Axial Force	-	7.93x2=15.86	7.85x2=15.7	lb_f
M_x Bending Moment	-	48.57	64.77	lb_f-in
M_z Bending Moment	-	5.2	2.53	lb_f-in

{f_{t,\ AN46} = 2 \times 47.78\ + \frac{3}{4}\ \frac{95.56\ \times 1}{0.625} }{= 210.23{\ lb}_{f}}

{f_{t,\ YA5} = 7.16 + \frac{3}{4}\ \frac{7.16 \times 1.6}{1.9375 - 1.6} }{= 32.62{\ lb}_{f}}

The source checks 210.23 lb_f at the AN4-6 side and 32.62 lb_f at the HL18PB/HL70 side against the same 4,080 lb_f and 1,400 lb_f tensile allowables; both pass.

Angle Beam

LOAD SOURCEFWD Support Angle joint reactions

IDEALIZATIONL-section simply supported beam · distributed joint load

DOWNSTREAM JOINT14 × HL40/HL70 pin-collar fasteners

Loads from the FWD support-angle joint are represented as distributed load along the Angle Beam. Peak components from separate cases are conservatively enveloped before the downstream joint and member checks.

Angle Beam idealized distributed loads and applied moments.

Plane	XY		YZ
Direction	+	-	+	-
Distributed load	2.9/9.46=0.31	32.62/9.46=3.45	69.7/9.46=7.37	95.56/9.46=10.10
Bending Moment	3.14	3.17	12.48	12.61

Angle Beam governing reactions, axial load and bending moments.

Direction		+	-	Unit
R_x Reaction Force	End A	1.64	16.48	lb_f
R_x Reaction Force	End B	1.30	16.16	lb_f
R_y Reaction Force	End A	15.86/2=7.93	15.7/2=7.85	lb_f
R_y Reaction Force	End B	15.86/2=7.93	15.7/2=7.85	lb_f
R_z Reaction Force	End A	47.06	34.16	lb_f
R_z Reaction Force	End B	48.50	35.56	lb_f
Beam Axial Force	-	15.7	15.86	lb_f
M_x Bending Moment	-	329.25	241.90	lb_f-in
M_z Bending Moment	-	11.48	111.90	lb_f-in

The 14 × HL40/HL70 connection is also checked for local tension-clip action. The resulting source tensile demand is:

{f_{t,\ ARV5} = 2.94\ + \frac{3}{4}\ \frac{32.64 \times 1.6}{2.39} }{= 19.33{\ lb}_{f}}

19.33 lb_f is small relative to the 1,350 lb_f source tensile capacity of the HL40 pin in this configuration.

Combined member stress is checked against AL 6061-T6511 tension/compression allowables:

{M.S}_{t} = \frac{38}{19.92 \times 1.5} - 1 = 0.27

{M.S}_{c} = \frac{34}{13.87 \times 1.5\ } - 1 = 0.63

\boxed{{M.S}_{t} = 0.27}

→ PASS

Local flange stability is retained because it is a distinct failure mode. The source computes a 31.06 ksi crippling stress and compares it with the governing 15.36 ksi compressive demand:

$F_{Crippling} = \frac{0.316\sqrt{34 \times 10^{3} \times 9.9 \times 10^{6}}}{\left( \frac{\frac{3 + 1}{2}}{0.1875} \right)^{0.75}} = \boxed{31.06\ ksi}$

{M.S}_{Crippling} = \frac{31.06}{15.36\ \times 1.5\ } - 1

\boxed{{M.S}_{Crippling} = 0.35\ }

→ PASS

Tee Clip

The final interface distributes the Channel Beam reactions into the Tee Clip and adjacent stringer attachment. The source deliberately ignores several available fasteners when distributing load, providing a conservative joint screen.

The previous analysis of the Channel Beam has shown that the maximum reaction forces carried by the all 5x18PB/HL70 (YA5) Pin-Collar Fasteners are:

Along the positive direction: f_x=32.61 lb₍f₎_f, f_y=15.86 lb₍f₎_f, and f_z=95.58 lb₍f₎_f.
Along the negative direction: f_x=2.91 lb₍f₎_f, f_y=15.70 lb₍f₎_f, and f_z=69.71 lb₍f₎_f.

For conservatism, it is assumed that:

The loads belong to the same loading case, while these loads came from different loading cases.
Fasteners No. 3, 4, and 5 at the top of the tee clip are ignored.
Fasteners No. 1 and 3 at the leg of the tee clip are ignored.

Conservative Tee-Clip fastener demand retained from the source load distribution.

Location	Resultant fastener shear	Key local stresses
Top fasteners #1/#2	168.19 lb_f	280.09 psi shear; 945.11 psi normal
Leg fasteners #2/#4	60.07 lb_f	140.07 psi shear; 322.99 psi normal

Tee Clip · Top

Maximum shear load on the top: $f_z$ = 47.79 × 2 = 95.58 lb_f.

F_{s,top} = \frac{95.58\ }{0.125 \times 2.73} = 280.09\ psi

Maximum normal load on the top: $f_y$ = 161.26 × 2 = 322.52 lb_f.

F_{n,top} = \frac{322.52\ }{0.125 \times 2.73} = 945.11\ psi

Tee Clip · Leg

Maximum shear load on the leg: $f_z$ = 23.90 × 2 = 47.8 lb_f.

F_{s,leg} = \frac{47.8}{0.125 \times 2.73} = 140.07\ psi

Maximum normal load on the leg: $f_x$ = 55.11 × 2 = 110.22 lb_f.

F_{n,leg} = \frac{110.22}{0.125 \times 2.73} = 322.99\ psi

The tee clip is made from 0.125” thick AL 6061-T6511 Extrusion which has an Ultimate Shear Strength value of F_su=26 ksi, and a Yield Compressive Strength value of F_cy=34 ksi (referencing the corresponding table). Therefore, the tee clip pass by observation.

REFERENCES

Structural Methods & Allowables

MMPDS-15 - Metallic Materials Properties Development and Standardization
MMEAVS-2003 - metallic material-property basis used in the source report

Regulatory & Aircraft Load Basis

Federal Aviation Regulations - 14 CFR Part 25
DHC-8-100 Load Cases and Applied Loads

Fasteners & Hardware Data

Standards Committee for Hi-Lok Products - HL18, HL40 and HL70
NASM3-20 aircraft-bolt technical data

Classical Stress Analysis Methods

Analysis and Design of Flight Vehicle Structures - E. F. Bruhn
Analysis & Design of Composite & Metallic Flight Vehicle Structures - Richard Abbott
Roark’s Formulas for Stress and Strain - 9th Edition

Inertial Navigation and Surveying System Installation Structural Substantiation

INTRODUCTION

DESIGN ASSESSMENT

INSGPS Installation Components

INSGPS Installation Weight Estimation

CAD volume × material density

15% weight growth

(X,Y,Z) = (AFT, Right, Up)

Material Properties

Fasteners Allowables

LOAD CASES FORMULATION

Flight loads · FAR 25.321 and 25.331–25.351

Emergency landing context · FAR 25.561

Ultimate factor retained explicitly

CLASSICAL ANALYSIS

Inertial Navigation and Surveying Equipment

4 × AN3-7 bolts

3D rigid-body equilibrium

INSGPS Tray

Longitudinal tray response

Transverse tray response

Assign each reaction to the governing plane

Adjacent structure carries secondary torsion

FWD Support Angle

AFT Support Angle

Angle Beam

Tee Clip

Tee Clip · Top

Tee Clip · Leg

REFERENCES

Structural Methods & Allowables

Regulatory & Aircraft Load Basis

Fasteners & Hardware Data

Classical Stress Analysis Methods