1. 1
Society of Flight Test Engineers
44th Annual Symposium
STEM, Education Reform, SFTE, and You
Abstract
Daniel W. Hrehov PE
Boeing Test & Evaluation
Seattle, WA 98124 MS 14-KF
(206)276-7814
daniel.w.hrehov@boeing.com
Abstract
This paper will describe a critical situation affecting the technical workforce in this country, how
it relates to education reform, in particular STEM (Science, Technology, Engineering & Math),
and how professional organizations such as SFTE can engage and take steps to improve it.
The need for engineers, specifically US born aerospace engineers, will increase dramatically
over the next few years due to a combination of an aging workforce and previous cyclic hiring
practices in the aerospace industry. This coupled with high school students declining interest in
engineering and science related careers will result in this country's increased dependency on non-
US engineers, who have significant restrictions when working US defense projects.
After a short review of education reform efforts in this country to close the achievement gap
between the US and foreign countries, this paper will describe the unique role flight test
engineers have together with other professional aerospace societies and companies to awaken the
technology curiosity in our young people so that more would consider careers in engineering. It
will also include constructive ideas that individuals and organizations, such as ours, can
implement in support of local high schools encouraging STEM activities at their schools.
Note: The author’s thirty years of flight testing experience and recent completion of a Masters in
Teaching, which included a teaching certificate for high school physics, has provided a unique
perspective on this issue.
Paper and Presentation available at:
http://sftestemoutreach.wordpress.com/

2. 37th
Annual Society of Flight Test Engineers
Symposium
Reno, NV
11-15 September, 2006
‘Electromagnetic Compatibility (EMC) for Flight
Test’
Workshop Abstract
Daniel W. Hrehov PE
Flight Test Engineer
Boeing Commercial Airplane Company
Seattle, WA 98124 MS 14-KF
(206)655-1385
daniel.w.hrehov@boeing.com
One flight test topic often misunderstood is Electromagnetic Interference (EMI), its affect
on aircraft avionics and in what way it should be flight tested. In some cases, EMI has
been the source of much confusion and the cause of unnecessary airplane testing due in
part to its unfamiliar technical terms that don’t easily lend itself to traditional flight
testing procedures and partially to the notion that it is covered by someone else (the ‘EMI
experts’).
This presentation will explore the aspects of electromagnetic compatibility (EMC) as it
pertains to both flight test pilots and engineers in the certification of aircraft avionics and
electrical systems. It will attempt to raise the level of basic EMC understanding so that
flight test crews can be better interface with the experts of this highly technical topic. It
will provide a better understanding of electromagnetic interference (EMI) and the overall
picture of how aircraft are designed and tested to address electromagnetic compatibility
issues from a Flight Test perspective.
Some of the topics that will be covered are:
1. Basic review of electromagnetic terms.
2. Brief descriptions of the electromagnetic environment aircraft are subjected to.
3. How EMI is addressed in the regulations and compliance guidance.
4. Identification of various forms of electromagnetic testing.
5. Explain the role others play in the overall compliance.
6. Discuss our role as pilots and engineers in EMC testing.

3. Society of Flight Test Engineers Symposium
‘Safety Consideration Regarding Flight Test
Instrumentation Installations'
Workshop Abstract
Daniel W. Hrehov PE
Flight Test Engineer
Boeing Commercial Airplane Company
Seattle, WA 98124 MS 14-KF
(206)276-7814
daniel.w.hrehov@boeing.com
Just the mere presence of instrumentation wiring to a flight test aircraft can potentially
adversely alter aircraft systems. This presentation will explore the aspects of hazards
introduced by adding instrumentation wiring and sensors. It will include the safety
analysis of the data acquisition system, the instrumentation sensors and the
interconnecting wiring.
Some of the topics that will be covered are:
1. General safety analysis processes, FMEA and Fault Tree and Intrinsic
2. Passive and Active electrical isolation
3. Interfaces to Arinc bus data, voltage and discrete data types
4. Special areas such as pitot/static systems, flutter vanes and forcing function
generators, lightning considerations and fuel tank instrumentation.

4. Copyright  2000 by Daniel W. Hrehov
31st
Annual SFTE Symposium
“WHAT INSTRUMENTATION ENGINEERS NEED TO KNOW
ABOUT LIGHTNING”
Daniel W. Hrehov PE
Flight Test Engineer
Boeing Commercial Airplane Group
MS 14-KF
Seattle, WA 98124
(206) 655-1385
daniel.w.hrehov@boeing.com
ABSTRACT
Instrumentation Engineers are tasked with the designing, installing, maintaining and operating
the onboard data system for flight test airplanes. This requires an understanding of the many
types of sensors and their calibrations along with how they interface with the aircraft systems.
When sensors are located outside the pressure vessel, a path for lightning to enter the airplane
interior is created. The ‘safety’ aspect of that installation needs to be addressed based on sensor
type, duration of the installation and any adjacent instrumentation channels in the event of a
lightning strike. These issues need to be addressed before the instrumentation wiring is installed
and should be considered during the design or selection of the data system.
This paper describes the hazards of lightning to the airplane and the unique role the data system
plays. It covers a basic definition of lightning and aircraft zones and both the direct and indirect
effects created by the transient. It describes recent applications where lightning analyses and
protection were required and then covers typical protection schemes along with their limitations.

5. 32
nd
Anniversary Symposium
Society of Flight Test Engineers
Abstract
“Certifying and Flight Testing a Portable Data Recording System
for In-Service Use”
Daniel W. Hrehov PE
Flight Test Engineer
Boeing Commercial Airplane Group
PO Box 3707 MS 14-KF
Seattle, WA 98124
206/655-1385
daniel.w.hrehov@boeing.com
Keeping a fleet of commercial airliners maintained and ready for passenger service is a
difficult job that the Airlines of the world accomplish on a daily basis. There are times
when the cause for a nuisance type airplane problem cannot be found on the ground or
eliminated by a replacement of a suspected LRU or piece of equipment. Problems that
show up only in flight necessitate the need for a data system that can record data during
revenue service flight.
This paper will describe the activities involved in certifying and flight testing a portable
data recording system for use on revenue service airplanes. It will include a description
of the Boeing built Portable Airborne Digital Data System (PADDS II) along with the lab,
flight testing and certification activities required to obtain FAA approval for use in-
service. Certification activities that include Certification Plans, Safety Analysis, and
Qualification summary along with Certification Flight Testing will also be described.

6. Test Program Review: 737 Fuel Tank Inerting Using a Ground-Based Nitrogen Supply
Daniel E. Hedges
The Boeing Company
Flight Test Engineering - Propulsion
P.O. Box 3707/MS 14-KF
Seattle, WA 98124
206-655-2774
daniel.e.hedges@boeing.com
Daniel W. Hrehov
The Boeing Company
Flight Test Engineering - Nav/Comm
P.O. Box 3707/MS 14-KF
Seattle, WA 98124
206-655-1385
daniel.w.hrehov@boeing.com
Abstract
This paper will discuss hazards and alleviations put into place to safely install flight test instrumentation
sensors inside the fuel tanks. Due to the nature of fuel tank testing that was to take place, a detailed safety
analysis was conducted to determine the risks associated with the installed instrumentation. For this
particular test, the mere existence of the instrumentation installed in the center wing tank was the focus of
where the risk would be associated with, not anything to do with the flight conditions. This risk existed
whether the airplane was in the air or even just sitting on the ground. As long as the data system was
installed and powered up, the risk was there. This is counterintuitive, because flight test risks are usually
associated with the specific flight conditions, and in this case, straight and level flight was all that was
being done.

7. •·.
FLIGHT TESTING THE 747-400 FLIGHT MANAGEMENT COMPUTER SYSTEM
Roger K. Nicholson
Daniel W. Hrehov
Boeing Commercial Airplanes
Seattle, Washington, USA
Abstract
The latest commercial transport offering from the Boeing
Company, the 747-400, was rolled out on 26 January 1988,
first flew on 29 April 1988, and was granted FAA type
certification on 10 January 1989. The airplane features an
advanced flight deck, improved aerodynamics, advanced
engines, and new interiors. The radically improved cockpit
features an integrated display system, a flight management
system, and simplified and automated subsystems, resulting in
a state of the art flight deck.
This paper describes development and certification testing of
the Flight Management Computer System (FMCS) as develop-
ed for the 747-400. The FMCS features system and hardware
changes unique to the 747-400, as well as product improve-
ments and enhancements to earlier generation systems. The
latter encompass navigation, flight planning and map display,
together with performance-related and operational items.
Testing of the FMCS was a multi-faceted effort, incorporating
ground testing, laboratory testing, flight testing, together with
flights typical of airline operations.
A variety of data collection techniques were utilized for this
program. These included realtime monitoring via special
purpose test equipment, onboard data recording to magnetic
tape; onboard data collection to disk, flight crew observations
and comments, FMC memory interrogation, and last, but
certainly not least, manual notes written by flight test en-
gineers and FMC design engineers.
As with any development program, design refinements were
required, but the key elements for successful completion were
effective communications, and responsive engineering,
instrumentation, operations and test organizations. The
presence of experienced avionics flight test engineers on the
flight deck acquiring data for every flight also had payoffs.
Rather than being led by only reported symptoms, timely use
of human and engineering resources were applied to identify
and isolate problems associated with perhaps the most
complex avionics system of this airplane.
ACARS
ADAMS
ADC
ARINC
ASCII
ATC
BITE
CMC
CPI
DME
DOP
DRQ
EFIS
EICAS
EIU
FAA
Nomenclature
Aircraft Communications Addressing and
Reporting System
Airborne Data Analysis and Monitoring System
Air Data Computer
Aeronautical Radio, Incorporated
American Standard Code for Information
Interchange
Air Traffic Control
Built In Test Equipment
Central Maintenance Computer
Control Program Interface
Distance Measuring Equipment
Discrete Output Program
Data Request
Electronic Flight Instrument System
Engine Indicating and Crew Alert System
EFIS/EICAS Interface Unit
Federal Aviation Administration
FADEC
FDS
FMC
FMCS
FTCS
:FTIR
HSPCM
IDU
ILS
IRIG
IRS
IRU
LNAV
LOC
LRU
MCDU
MCP
MS-DOS
ND
PC
PFD
QRH
resync
SSM
swc
TIP
VNAV
VOR
Full Authority Digital Engine Control
Final Data System
Flight Management Computer
Flight Management Computer System
Flight Test Computing System
Flight Test Instrumentation Requirement
High Speed Pulse Code Modulation
Integrated Display Unit
Instrument Landing System
Inter Range Instrumentation Group
Inertial Reference System
Inertial Reference Unit
Lateral Navigation
Localizer
Line Replaceable Unit
Multipurpose Control and Display Unit
Mode Control Panel
MicroSoft Disk Operating System
Navigation Display
Personal Computer
Primary Flight Display
Quick Reference Handbook
Resynchronization
Sign/Status Matrix
Stall Warning Computer
Test Item Plan
Vertical Navigation
VHF Omnidirectional Range
Introduction
This paper describes the flight testing techniques used in the
development and certification of the Flight Management
Computer System (FMCS) for the Boeing Model 747-400. It
includes activities that started well before the aircraft's first
flight and continued through the flight test program. A brief
description of the 747-400 is presented, along with an over-
view of the flight test program. A variety of data collection
techniques that were utilized are described. Testing tech-
niques describing ground testing and instrumentation check-
out, laboratory testing and concurrent and dedicated flight
testing are reported. Post flight data reduction and analysis
are discussed emphasizing the need for rapid data turnaround.
The paper conclude_s with a discussion of some of the FMCS
issues revealed during flight testing and a review of some
recommendations for future FMCS testing.
Airplane Description
The Model 747-400, depicted in Figure 1, incorporates
evolving technology into one of the world's most modern and
fuel efficient airliners in commercial operation. Its design
embodies technological advances in aerodynamics, structural
materials, avionics and interior design. Along with re-con-
toured wing-body fairings, the most noticeable aerodynamic
improvement, designed to reduce fuel burn and extend range,
are the six-foot wing extensions with six-foot winglets.
Additional efficiency is incorporated in newly designed struts
and nacelles for the advanced Pratt & Whitney PW4000,
Genera! Electric CF6-80C2, or Roll Royce RB211-524G
engines which provide a minimum of 56,000 pounds of thrust
each. Use of advanced materials has allowed considerable
l i . 5- 1